If you don't mind doing work on it I would just worry about getting the best shell possible with a nice interior. The mechanical stuff you can sort as you go then.

Find something with a blown engine perhaps and then rebuild your own motor for it. Saw a nice tidy grey S2 88 spec not too long ago with a dead gearbox for £600. If somebody had the time and cash that could have been sorted and running againg without too big an outlay