If you hit 85, you have several cataclysm factions high enough to grab some gear. Visit those first.
Have a look here for help:
http://www.mmo-champion.com/threads/784509-Cataclysm-Reputation-Reward-Guide
Remember also that you can reforge DPS gear into decent tank gear now, since there's no more need for defense or similar specific stat. So you can grab DPS plate gear from the factions mentioned previously for your missing slots and tinker them into decent tank gear with high stamina.
Then you have crafted gear, there you may just want to look on Wowhead and ask in your guild if some blacksmiths have spare chaos orbs for you. For instance, the crafted tank shield is quite good and only costs one chaos orbs (and a few other expensive, but "soloable" components).
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SWTOR: 50 Jedi Shadow (Tank), 50 Sith Marauder (Annihilation).
LOTRO: Lifetime account, playing very casually.
WoW: Both accounts canceled for now.
GW2: Future Warrior.