Two things to keep in mind. First, when a piece of gear has sockets for gems, you can put any kind of gem except a meta gem in those slots. The only benefit you receive from putting the correct color gem in a socket is the ’socket bonus’, which often is not worth the benefits you get from good gems. Remember;

Solid Star of Elune (+12 Stamina [Blue])
Delicate Living Ruby (+8 Agility [Red])
Shifting Nightseye (+4 Agility, +6 Stamina [Red/Blue])
Enduring Talasite (+6 Stamina, +4 Defense [Yellow/Blue])

are your best choices of AH gems.

Which you choose really depends on whether you want to boost your health, your dodge, or your defense against crits.

Another thing to keep in mind is your early choice of Aldor or Scryer as your faction in Shattrath. If there is a pattern or item from reputation that you just have to have, then that’s fine. Go with what you like. But keep in mind that each faction has it’s own unique quest chains, that provide rewards that the other faction does not have access to. And the Aldor Netherstorm quest chains have one of the best Leather shoulder pieces for early bear tanking available as a quest reward. If you haven’t made your choice yet, check out the quest rewards below and keep that in mind.

Two Handed Weapons

Braxxis Staff of Slumber
A random BOE world drop and equippable at level 64, it may surprise you to find out that, until you reach level 70 and exalted with the Cenarion Expedition, there is no finer bear tanking weapon. 550 armor, +39 Stamina and +234 AP in Cat or Bear form.

Earthwarden
The reason you work so hard to run every quest for Cenarion Expedition reputation, in Zangarmarsh and in Blades Edge Mountains, is to claw your way to exalted and get this two handed mace. The best tanking mace prior to end game drops. 500 armor, +39 Stamina, +27 Defense, +24 Feral Combat Skill, and 556 AP in bear or cat. It may seem close to Braxxis, but with the defense, AP and hit you’ll hit more often against level 73 elites, you’ll have better crit protection, and you’ll hit much harder. All excellent ways to help hold aggro.

Head

Stylin’ Purple Hat
An excellent crafted hat for bear tanking that is BOE, and fairly easy to find on the AH. You can start using this at level 69.

Neck

Necklace of the Deep
Another excellent BOE crafted piece, that has amazing flexibility. With two Shifting Nightseye it provides a total of 29 Agility, 32 Stamina, and +3 Hit rating. With two Delicate Living Rubies it provides an incredible 37 Agility, 20 Stamina and +3 Hit. And with two Solid Star of Elunes in there it’s +21 Agility +44 Stamina. Better still, this is equippable at level 65. A very flexible must have for the starting bear tank.

Shoulder

If you are Aldor rep, then you are in luck. There is a quest reward that is a very nice piece of gear for your starting tank.
Cleansed Fel Pauldrons
These shoulders are not bad at all, and a lot better than any other alternative you are likely to have prior to instance runs. The quest chain that results in these shoulders starts here. Once you have these shoulders, you are good until either Black Morass or Sethekk Halls drops (see below).

If you are already Scryer, then you’re alternatives look more like this to start;
The Dreamers’ Shoulderpads
A fairly common world drop reasonably priced and often found in AH, useable at level 68. Since they ARE so easy to find, this is the item I recommend you start with. There are a couple of better shoulders from early instance runs such as the Mantle of the Dusk-Dweller from Keli’dan the Breaker in Blood Furnace (normal mode), but if you pick up The Dreamers’ Shoulderpads, you can hold out until you are ready for one of these two;

The Sun-Gilded Shouldercaps
Drops from Chrono Lord Deja in Black Morass.

Even better the Shoulderpads of Assassination
Drops from Talon King Ikiss in Sethekk Halls. The Shoulderpads of Assassination, with two yellow gem sockets, is your best non-PvP reward tanking shoulder option prior to Karazhan, but remember that these are Rogue set shoulders… please do not ‘need’ them without talking politely (oh, so politely) to any Rogue that may be in your party. If they need them, they should have them first.

There is one last option that is still, in my opinion, a casual route you can work towards that provides better shoulder armor than any of the other options listed so far.

Grand Marshals’ Dragonhide Spaulders or High Warlords Dragonhide Spaulders
Obtained with 10,098 honor and 20 Arathi Basin marks from PvP. This is non-arena gear. If you get involved with Arena matches, the Gladiator set shoulders are even better, but harder to save towards. I have not personally run PvP since pre-BC, but I have been told that it is possible to earn 2000+ honor in one night, from running Alterac Valley a few times, and of course you get 1 Arathi basin mark per loss or 3 per win in that battleground. Your mileage may vary, but this is a reasonable time investment for such a nice shoulder item.

Back

An excellent early instance drop Cloak is;
Bogstrok Scale Cloak
The Bogstrok cloak is an outstanding cloak that will last you well into the game. With 271 armor, +22 Stamina and +16 Defense it is quite outstanding. It drops from Rokmar the Crackler in Slave Pens, normal mode.

If you don’t run instances, then a slightly weaker option is;
Cloak of the Valiant Defender
Still a very nice cloak for bear tanking, and a quest reward from Ar’kelos the Guardian, the end of a long Netherstorm quest chain that starts here. The Cloak of the Valiant Defender has 262 armor, +21 Stamina, and +15 Defense rating.
It’s a very nice cloak for bear tanking, not quite up to the Bogstrok Scale Cloak but very close if you haven’t gotten lucky on the drop.

I’ll be honest with you, however. At the time of this writing, I have still not completed that quest chain.

Instead, I saved the money and farmed the mats for;
Resolute Cape
A BOE crafted epic cloak. This requires a Primal Nether to craft, so I personally paid a Tailor 150 gold for their crafting and their BOP Primal Nether to make it for me. Your mileage may vary, so do what works best for your time investment. All in all, it may not be that big an upgrade over the Bogstrok Scale Cloak, but at the time I wanted a Cloak for tanking and I had very little time for instances or lengthy quest chains. At the cost of some material farming and some gold, I was able to get a nice upgrade.

Once you have the Bogstrok Scale Cloak, the Cloak of the Valiant Defender, or the Resolute Cape, your next best upgrade prior to Karazhan is;
Thoriumweave Cloak
Drops from Mechano-Lord Capacitus in the Mechanar, normal mode. There are other better cloaks as well, by all means pursue them. But if your time is limited you might want to let your old cloak last you until you can run the Mechanar.

Chest

For Chest, there can be only one option;
Heavy Clefthoof Vest
This is just one of the three crafted BOE Heavy Clefthoof set pieces. Each of the three pieces can be found often on the AH, and are truthfully your best bet for a long time, if ever. 500 armor, +24 Defense, +45 Stamina, two yellow sockets and a blue socket make this an unbelieveable bear tanking chest piece. Requires level 70, as it should. My recommendation on this one is to ignore the socket colors and either put three Solid Stars of Elune or even three Shifting Nightseye on this, to really pack on the health and dodge. With three Solid Star of Elune, this gives you 500 Armor and +81 Stamina, and if that doesn’t make you cry with joy I don’t know what will.

Wrists

For wrists, I wish I could give you more options, but there really is only one choice prior to serious raiding.
Umberhowl’s Collar
A quest reward in Shadowmoon Valley. It is the final reward from a very, very long quest chain. The quest starts here, on through to here, which gives you three quests, each to fnid a different son. You want Borak, Son of Oronok, which is the quest chain for the Third Fragment, which starts here, and finally culminates in this.
Yes, it is a very long chain. However, along the way there are many rewards, and from what I remember as a feral druid almost the entire thing is soloable depending on your gear at the time. The Umberhowl’s Collar is famous for being a ridiculously nice bear tank bracer that you will wait a LONG time to ever find an upgrade for.

Hands

Again, there is only one choice for starter bear tank gloves;
Verdant Gloves
A quest reward in Shadowmoon Valley. The quest chain starts here (Scryer) or here (Aldor), depending on your faction.

Make no mistake, this is a very hard quest chain. Before it is done, you will need to make a trip to the Arcatraz. You do not need to actually kill anyone in Arcatraz, you can be brought into a party that has already completed the Arcatraz and cleared it, since all you need to do is to find the body of Seer Udalo, the NPC for that part of the chain to complete it. But keep in mind that you will have to enter the Arcatraz to do this to proceed.
Yes, I know this does not seem like an easy path for a casual player. The reason I insist that this is the only choice for a 70 druid starting his tanking set, is that these gloves are equivalent to Tier 5 armor for bear tanks. There is, short of a drop in Shattered Halls (Wastewalker Gloves) that actually have worse armor but better agility, no better gloves for you prior to serious end game raiding.

Waist

Again, your best option is a quest reward in Shadowmoon valley;
Manimal’s Cinch
A green item quest reward that is ridiculously good for bear tanks. Providing massive armor, high strength, good agility and stamina it is very nice indeed.
The quest chain starts here. Why yes, yes you saw that correctly. This item is a reward from one of the early quests in the exact same chain you must do for your Umberhowl’s Collar. Isn’t that sweet? You do one long quest chain and get TWO of your best bear tanking pieces! Isn’t Blizzard nice?

Legs

Heavy Clefthoof Leggings
This is your best choice. Crafted, kick ass, and found often on the AH. Do yourself a favor, and go buy them. 503 armor, +33 Stamina, +29 Defense, and 2 blue sockets, one yellow socket. Again, stack three Solid Star of Elune in here and have a total of +69 Stamina from one piece, or add some Nightseye to boost your Dodge. Useable at level 70.

Feet

Heavy Clefthoof Boots
Again, best choice. Crafted, kick ass boots often found at AH. 394 Armor, +30 Stamina, +21 Defense, and one yellow and one blue socket.

Rings

I hate rings. There are very few easily obtained true bear tank rings. And often, you are competing with warriors that want to ‘need’ the drops because they ‘might be good if they decide to respec someday’ /cry.

Delicate Eternium Ring
Crafted BOE so it can be found on the AH. Nice ring, it provides +25 Agility, +15 Stamina and +16 Dodge. It is unique, there can be only one equipped.

Arcane Loop is a rare BOE drop in Netherstorm sometimes found in the AH, and it can have many different kinds of stats. If you are lucky you might find a ‘Of the Monkey’ or ‘Of Stamina’ in the AH, which are also good tanking choices.

Mok’Nathal Clan Ring
The first (and easiest) instance drop bear tanking ring. It drops from the chest that appears after killing the end dragon boss in Hellfire Ramparts. It is notable that it is NOT unique, and therefore you can wear two of them. 180 armor, +16 Stamina, and +14 Resilience. Pretty darn nice for bear tanks. Some 70 druids have been known to stealth to the end boss and solo him just to farm for two of these rings.

Iron Band of the Unbreakable
The next instance run ring drop to look for, it drops from Lieutenant Drake, the first boss in Old Hillsbrad (Caverns of Time) in normal mode. It also does not say unique-equipped, so I believe you could have two of these equipped at once. However, as you will see next, if you are entering Karazhan a much better ring that is a quest reward may soon be yours, so plan ahead before farming for two of them. Iron Band of the Unbreakable has 170 armor, +27 Stamina, and +17 Defense. IMO, Old Hillsbrad is extremely fun, fairly quick, and running it at least once unlocks Black Morass for you to play in, where some really nice drops also happen to be found. I enjoy running it more than any other except Black Morass. You may find it fun to come here and try for two rings, especially if you never expect to be part of a Karazhan guild.

Violet Signet
A ring that is the Karazhan reputation reward from Path of the Violet Protector. When you reach friendly with the Violet Eye, the faction that gives you rep for Karazhan quests and kills, you can choose one of four quest chains from a quest giver standing just outside the entrance to Karazhan. The Path of the Violet Protector gives you this ring. Each time you increase a reputation rank with Violet Eye, your Ring gets upgraded to incredible levels. If you ever do enter Karazhan, after completing the long attunement chain, you will be only at most three nights worth of runs from getting friendly and having this ring. Make no mistake about the quest chains, choose the Violet Protector and get this ring. At the lowest (friendly) level it already has 294 armor, +27 Stamina, and +13 Defense. And it rapidly gets much better.

Ring of Unyielding Force
If you are skilled and fairly well geared, which if you have most of these pieces you will be, then you might be running some heroic instances. When you kill any boss in a heroic instance, every member of the party earns 1 Badge of Justice. For 25 Badges of Justice you can purchase this ring from the vendor in Shattrath City. As a bear tank, it is one of the few rewards you can buy with Badges of Justice that really kick ass. 294 armor, +31 Stamina and +22 Defense.

Trinkets

If you’re lucky, you still have;
Mark of Tyranny
from a quest chain in Azeroth. That sucker is still good, even at 70. 180 armor, +10 Arcane Resistance, (useful in Karazhan), and +12 Dodge rating.

If you have the gold, then keep an eye out at the AH for the BOE
Badge of Tenacity
I have seen it around 1500g, but is worth it at 2000g. If you work at the Ogri’la quest chains, you can earn the right to take on the SOLO event that has a chance to drop the Depleted Badge, from which this trinket is made. The Badge of Tenacity is wonderful. Well worth the money, or the time you spend in farming it. 308 armor equipped, (yes, 308!) and on use it increases Agility by 150 for 20 seconds. A very nice ‘I need more dodge NOW while healer regains mana’ item.

There are many other trinkets, that each do strange or unusual things. Engineering has trinkets, as does PvP and reputation rewards, but the thing to look for is one that either gives you a very large Agility, or a nice chunk of Stamina.

The Darkmoon Card: Madness and Darkmoon Card: Vengeance both have other effects, but mainly give you +51 Stamina when equipped. Also, enchanters can make the Smoking Heart of the Mountain for an armor boost and resists. You’ll have to use your best judgement and consult your professions for your best options when considering trinkets.