Quick auction house check with my level 84 tanking paladin:
Cheapest piece of iLevel 359 epic tanking gear on the AH: 30K gold.
Cheapest piece of iLevel 359 epic cloth caster gear: 3k gold.
Number of blue level 85 tanking gear items on the AH: 0
Number of blue level 85 dps items on the AH: 213
Number of tank items I can craft with my maxed out blacksmithing skill before running heroics: 0
I think I'll cancel my plan to gear up that paladin for tanking heroics. My other characters were so much easier to gear up.