I will add to this: Buy the best car you can afford, $10K-$15K is probably about right, just don't expect a "perfect" car, these are 45+ year old cars and are bound to have small issues no matter the price.
I went the cheap route, paid $4k for mine, lots of rust, didn't run, and I've put at least $20k into it (lots of mods), and it's still not on the road (really close though, although I'm sure I said that last year too)