AOD's hardly hold up behind smaller motors. When I had the supercharged 3.8L (out of 90's T-bird) in my ranger it ate a fresh AOD within 3 months. IF you MUST run an AOD then get the biggest cooler you can find (mine looked like a mini radiator!) and check/change the fluid a lot.

As for the gearvendors. I have seen used ones for $800 or so. Plus they have an adapter exchange program which lets you trade in the adapter for another, so if you find one for a TH400 or something you can trade that adapter for the c6 one...