Maybe buy a Toyota or Honda ? My mom had a 1996 Camry that I sold 3 years ago and nothing was wrong with it !We are running into this at the dealership level all the time. Anything over 10-12 years old, model specific PCMs, BCMs, ABS modules and such are no longer available. We don't touch used electronics at all, no matter how much someone begs.
I really haven't heard of anyone replacing computers on a car, but my family does mostly stick to Toyotas and Hondas.