Last one on ebay hit just under $300. I'd say $250-$350. It's a game someone either wants or doesn't, not an impulse kind of game purchase. I think they are neat.
I'd say the usual price range would be $150-350. But if you really want it and it's in nice condition, pay what you think is reasonable. just be aware that you will not be likely to sell it for a ton of cash. So only pay more than market value if it's a game you really want.