Yeah, I've got $20 burning a hole in my pocket and I'm looking to buy a South African diamond mine.
It doesn't matter how old a car is, you need to figure that most used cars are sold when they need $1000 or more in repairs to make them close to 'right' (no matter what make or model.) That's the safest bet.
Hmmm...Quattro or SVX... interesting. Which one has higher maintenance costs? I had two Audis years ago and no matter how inconsequential a part was it seems the dealer pricing always started at $82. Seriously. Tie rod end = $82, sunroof cable = $ 82, rubber radiator mounts = you guessed it, $82... ad infinitum.