$400 - $500 for a really nice one would be a retail price range.
Can you play it and look at it before you buy? Check out the backglass from the backside, is it flaking or missing chunks of paint? How's the playfield? Worn to the wood in several spots, or only small wear spots in one or two locations? Play it, everything seem to work?
If the backglass is good, playfield is good and it plays, with perhaps only a few small problems, then under $200 is a very good price indeed and you should snap it up.
D