A buddy of mine has a used Mossburg 500A Cruiser 12GA pistol grip with a heatshield in excellent condition (has only had a box or two of ammo shot through it). Neither one of us know what it is worth. He paid $264 for it back in 1994. What's a fair price for this used shotgun (for him and for me - I don't want to underpay or overpay)?

I basically want to buy it for MORE than they would would give him at a gun shop, but LESS than I would pay at a gunshop.

Used Mossbergs don't go for much. I think $200 is about right for a used 500 in a store. Maybe less if it only has a pistol grip, since that is not a very popular configuration.