I would assume that since he is not giving you a price, that he probably wants to get as much as he can but knows that it is not worth much. I would say, ask him if he was looking to get $300 or what? Not commiting to a price but letting him know that you don't plan on paying tons and it kind of draws him out to put a price on the table. If he says yes, you could try to go lower or if he wants more then you can ask for $500