It's worth whatever someone will pay him for it. The market for these items varies wildly depending on several factors. Where he got it and how much he paid for it are irrelevant- If you inherit a Mercedes from your uncle, should you be obliged to sell it to me for 5x what you paid? Personally, I would go check it out and go from there. When I list something on say Craigs list or local paper I expect to negotiate 10-20% . If someone wants to come look and make an offer in person they can offer whatever they like- I retain the right to refuse sale. Lowball offers by e-mail are ignored. My experience with low offers is that they are either no-shows, or when they arrive to pick up the item they tend to want to niggle the price down even further, at which point they are shown the door.
