OD tranny hard to come by?

I talked about OD with my trans guy just this morning. He says 1990,91,92, A500 is all I should look for.
Parts yard prices have ranged from 350 to 700. The 350 quote is a 4 hour drive away. :( That donor ( 91 van ) shows 188K miles.
Rebuild if needed is 750 which includes reman'd torque converter.
Still atleast half of the GV cost at all done.