I know the owner of the local AMCO. I brought my 1996 Z28 in (37K miles at the time) because the the transmission had over heated. This transmissions was properly serviced less than 6 months prior. The cause of the over heating was my son driving the car in low, rather than drive.

Anyway, the local AMCO shop had a flat fee of 79 bucks to pull the pan and tell me what was needed. I was offered different 3 levels of repair service with 3 different warranty's.

I had the work done and have not had a problem since.

If you are strapped for cash, best bet would be to invest the 79 bucks in a simular diagnostic service. The parts to fix your tranny could be all just soft parts and may not even require the tranny to be pulled. If the parts involved are hard parts and require the tranny to be pulled, the costs will be significantly more.

As far as used tranny's or "rebuilt ones" I'm sure there are success stories out there, but it's hit or miss if your story will wind up as succesful going used or blind rebuild.