There's a lot of Mana Stone Tier 6+ at AH (server Govinda) with dirty stats (all I). Tiering with that stones is worth?
Yes, you tier with those... It is really a time-money tradoff as is most everything in this game.
To make a T6 stone, it costs...
1) 9 fusion stones. Cheap dirty ones are OK, because tiering with anything else is prohibitively expensive. So, 2K x 9 = 18K
2) 9 tier 4 items. As mentioned, in Limo, they sell T4s at vendor. If you can get to Limo, it is 4K per, so total is 4K x 9 = 36K
3) 13 AT charges. That is where it gets expensive... AT charges are usually gotten with phirius, so it would cost 390 tokens, or 4 days worth of token. That is why most people run alts. Alts get 10 ATs and with 9 dailies, they get needed 13. No money investment here, but you need to level alt to L10 to get your AT unlocked.
Overall, T6 building cost is 54K... unless you can't get to Limo. In that case, they sell T4 belts on AH for 8-10K. That bumps the cost to about 100K for T6.
That should help you decide if you would rather buy the stones on AH or make your own.
Now, lets see the costs overall. I'll assume Limo and I will round cost down from 54K to 50K since you get some junk that alt can sell..
T6 = 50K x 3 = 150K (3 alts)
T7 = 150K x 3 = 450K (9 alts)
T8 = 450K x 3 = 1.35M (27 alts)
T9 = 1.35M x 3 = 4.05M (81 alts)
T10 = 4.05M x 3 = 12.15M (243 alts)
Ouch... I think I am going to have to settle for a T9 for my big weapon.