Khorium Pants, Khorium Belt and Khorium Boots: This "healing for beginners" set can also double as shockadin or AOE prot grinding gear. Non-blacksmiths can wear it, but to get the big healing bonus, you need to have at least 350 blacksmithing. The whole thing will take 13 Khorium Bars, 9 Primal Mana, and 9 Primal Water -- but unless you're leveling up blacksmithing yourself, it's probably cheaper to buy the completed pieces in the AH. So many blacksmiths use these for leveling up that most of them are willing to take a major hit on the price for a skill point.
Blessed Bracers: This extremely rare drop recipe will cost you nearly a thousand gold in the Auction House, but since you can turn around and sell the finished product for just as much, it's definitely worth the cash -- especially if you craft a set for yourself. It's well worth the mats (which include 15 Primal Water, 2 Primal Might and a Primal Nether.)
Hammer of Righteous Might: An underwhelming hybrid mace that would be much better as a fast one-handed tanking weapon for protadins. Plus, the material cost is ridiculously high, and the recipe is nearly impossible to find (it only came into play in 2.3). Leave it for the boomkin, unless you're planning on doing holy DPS using SoR against single targets.
Hand of Eternity: This one-handed healing mace looks good on paper, but is really only slightly better than the Gavel of Pure Light from exalted Sha'Tar. If you find yourself high on cash but low on Kara groups, give it a try, but it might not be worth the effort for the proletariat masses. Primal Mights don't come cheap.
Dawnsteel Bracers: Unfortunately, the plans for these bracers are BOP and buried deep inside the Black Temple. Fortunately, the end product is BOE! The four Hearts of Darkness will cost you a pretty penny, unless you have numerous guilds on your server who've made all their resistance gear for BT. Nevertheless, haste rating is invaluable. Go for it if you have access to Hearts of Darkness or a LOT of cash.
Dawnsteel Shoulders: This reversal of Dawnsteel Bracers is a BOE recipe with a BOP product. The stats are killer for paladins, though. Expect to shell out 700g for the recipe and an extra thousand or so for the mats. Amusingly, this is actually less than what the Dawnsteel Bracers sell for in the AH. Definitely snatch up the recipe if you think you can handle the mats.
Heavy Earthforged Breastplate: This hybrid warrior BOP plate requires you to be a 330 skill Armorsmith to craft it -- and that's about the only downside. The mats should run you less than 30g (8 Adamantite Bar and 4 Primal Earth), the stats are okay for beginning to tank, and it's learned from a trainer. To make it last longer, ignore the gem bonus and outfit it with 12 stamina gems.
Felsteel Gloves, Felsteel Leggings, Felsteel Helm: The tanking equivalent of the Khorium set, Faith in Felsteel requires 22 Felsteel Bars. You should be able to get that pretty easily if you're leveling mining as well. However, the recipes all drop in instances, so once again, the AH is your best bet unless you need the skill points. You can get the whole thing for less than 150g. Non-blacksmiths can snag it too, but they'll miss the 25 strength bonus. Note to self: Buy this for my jewelcrafting protadin when I get home!
Breastplate of Kings/Bulwark of Kings/Bulwark of the Ancient Kings: This upgradeable tanking/damage chest is sadly inferior to the upgradable DPS weapons. Like many plate items, it tries to fulfill two roles at the same time and fails at both. The armor and "Last Stand" ability make it tempting, but if you have the ability to get Nether Vortices, you can probably find something more suitable.
Bracers of the Green Fortress: If you've just hit 70 and are looking for good tanking bracers, these are what you want to aim for. You can't farm the recipe -- they're a world drop -- but the reagents aren't too tough to come up with. Pick up the recipe if your server has a lot of protadins, and you can make some nice green providing the crafting and Primal Nether. If not, suck it up and pay a crafter the fee.
Gauntlets of the Iron Tower: Pass. The Felsteel Gloves are equal or superior for tanking and much cheaper.
Helm of the Stalwart Defender: Hey! What did we say about resilience on PvE items? But it's a great helm otherwise, so we'll forgive it. The armor and stamina can help bring you up to the level of a warrior, the gem slots can all be socketed with Solid Stars of Elune, and it looks ... well, unless you're a belf or draenei, it's going to look pastel. The recipe is a world drop, but it's worth the pickup.
Oathkeeper's Helm: ... or you can go for this. It's a little more pally-specific, with int and spell damage on it. Unfortunately there's not much avoidance on it, so it might be best saved for pallies who have adequate block/dodge/parry on their other items. And yep, it's another world drop with high material costs and an awful skin.
Belt of the Guardian: Eeeeexcellent. High armor and stamina, plus defense, shield block value and a little damage/healing for fun. The mats are easy ... except for the two Nether Vortices. Those, plus the fact that the recipe is BOP and drops in SSC, means that either a) you have to be in SSC to craft it or b) you have to have a contact who is in SSC, has this recipe, and can convince their guild to give them Nether Vortices to make something to sell. Needless to say, its AH cost is around 2000g.
Boots of the Protector: This is another pally tank SSC recipe, but it's a BOE recipe with a BOP result. Luckily, it doesn't require Nether Vortices (only a Primal Nether and a ton of Primal Water), and the recipe is actually cheapish -- 340g. Unfortunately, you can't sell the result. The defense, shield block rating and dam/heal make this a bargain unless you can afford ...
Red Havoc Boots: The pattern is BOE from SSC and the Eye. The boots are BOP. You need two Primal Nether and a ton of Primal Fire. They're quite a bit better than Boots of the Protector. However, the recipe costs about four times whan Boots of the Protector costs. If you're sure you want them, you might be able to pick up the recipe on the AH, but it can be difficult to find on some servers.