Soldato
There's plenty of suitable MR2s about and plenty more being broken as prices are pretty low right now.
Ultimately the big deciding factor on the value of an mr2 is the condition of the bodywork as parts are easy to come by for sorting out mechanical stuff. As a result getting a cheap ratty looking one is easy, as is getting an expensive minter. The difficult part is finding a tidy car without paying too much for it. As you're only after a track car anyway this isn't a concern.
Ultimately the big deciding factor on the value of an mr2 is the condition of the bodywork as parts are easy to come by for sorting out mechanical stuff. As a result getting a cheap ratty looking one is easy, as is getting an expensive minter. The difficult part is finding a tidy car without paying too much for it. As you're only after a track car anyway this isn't a concern.