Do you even know what it costs to build a decent reliable single turbo supra? Parts aside look at labour costs and then look at mapping. This is why most get broken for parts. Owners don't want to sit around waiting for that inevitable sale or have to put up with all the tyre kicking dreamers. They want to release cash quickly and parting out a car is the best way to do it with a lot less hassle.
The problem is that the OP is being unrealistic in my opinion, the days of cheap Supras are gone and the more he dig his heals in about this the worse it will get. Old school Jap motors are all increasing in popularity and in price with decent examples becoming difficult to find. Try to buy a decent R34 GTR for under 50K now, you will be hard pressed to find one.
Why shouldn't this trend translate to the Supra? It's been far too cheap for far too long, owners used to talk the prices down because there was a glut of them but as I said above those days are gone.
If the OP can't budge on price he needs to go back a re-evaluate what is important to him. How can he expect to insure, maintain and pay for the running costs of a single TT6 (now single auto) if he can't afford the market value?
Champagne tastes on a beer budget.