I've seen them sold for $40, sometimes more sometimes less. It depends on the person you are buying from and why you are buying it. Price also depends on your location. Around here they may sell for less (or more) than what they sell in your area.
I've seen $50 as a typical price for average stock. I think you might get one for less, if you got a good deal. If it was from exhibition stock, who knows how much they'd want.