Alex said:
I think you can pretty reasonably hit 25,000 health before starting raids on your Paladin. That'd be my goal.
I'm up to 26,000 unbuffed myself with badge loot/heroic boss epics/heroic blues and a few AH items. That's without any pure stam gems too since I can't afford them due to my trinket choices (and one of my rings) having no def.
It'll be a lot easier with the new stamina enchant to bracers and the sockets being added to the Tempered Titansteel Helm. That helm will be go from mediocre to completely bad ass tomorrow, so nab it.
I like to go in fairly over prepared though, uh... well, not that I'll ever get to tank a raid ever, since it's my offspec

Stupid, reliable raid tanks! Our outtings need more Hammer of the Righteous!
GONG!!!! Best sound effect in the game.
I'm barely over 26k unbuffed right now without any raid gear, but that's also with the JC-only tank trinket and prismatic stamina gems. Aside from wrist/shoulders I have about the best you can get pre-raid for tanking in all slots, so it's not that easy to hit 25k. I just say 22k is a good base because with full 25man raid buffs you'll be at like 28k, with 10man raid buffs you'll be at 26k. with the game down for maintenance I can't link to my armory, but I can basically name my gear: Tempered TS helm (revered AC enchant), emblem of heroism neck, Pauldrons of Recon (quest reward from HoS, with +12 stamina armor kit), Tattered Castle Drape, revered wyrmrest chest, bracers from the wyrmrest daily on top of the Nexus (+6 all stats enchant, replacing with stamina after this patch), Refined Ore Gloves (+20 hit rating enchant), emblem of heroism belt, heroic VH pants (with jormungar leg armor), revered wyrmrest boots (with 22 stamina enchant), heroic HoS tank ring off the Maiden boss, Titanium Earthguard Ring (solid sky sapphire socketed), Dabiri's Enigma (need like 6 more defense from some other slot first before I can drop this for Lavanthor's Seal), JC-only northrend crab trinket with nothing but stamina gems socketed, Red Sword of Courage (titanium weapon chain for now, stamina enchant post-patch probably), heroic CoS shield (+18 stamina enchant), Libram of Obstruction. If it has blue sockets, it has +24 stamina gems in it. Sometimes, if it has red/yellow sockets, it has +24 stamina gems in it. For the most part I gemmed stamina when it would give me socket bonuses that were +defense, and gemmed +defense when it would give me socket bonuses that were +stamina.
All that + 450 mining + stamina enhancing talents puts me at 26144 hp. Probably easier to get a couple hundred more if you cheat and play alliance, since I'm sure humans/dwarves/draenei start out with a few more hp and possibly gain more stamina, too. The thing is, even with a meta socket added to tempered TS helm, the best meta doesn't give stamina. Although I think the socket bonus is like +6 stamina, and maybe it has another socket besides the meta. But this patch will also increase the bonus stamina from Sacred Duty, so I guess post-patch if you can get all that gear I have and enchant it for stamina, 27k unbuffed wouldn't be hard to get.
and on an unrelated note, I think I'm going to respec my DK from frost to blood after servers are up. I probably won't go full 51+ blood yet since I only got my DK to 66 and I'd like to keep Annihilation, but I'm a little tired of frost's burst/crit procs and overreliance on one specific school. Blood is pretty much all physical, but at least it should be easier to kick ass with, have less downtime, and I can proc sudden doom to have a simple RP dump.