Well if you can't spend too much money, I would go with something like the low end of the Canon EOS series or a lower end Nikon SLR, N75, etc. Or even a used version of those camera bodies.
Anyway, what is more important than the camera body, is the lenses. If you skimp on the glass no matter how the good the camera body is the images will still have a loss of resolution.
Edit: If you're going for 70's old, look for the Olympus OM series, you can still buy new glass and they were a revolutionary camera (in terms of light metering tech) at the time they were released.