Get what you can for it. Keep in mind anyone can go to WalMart and get a new radio for well under $100 that may have just enough modern features to make that 7 year old radio irrelevant. You never know what a bit of effort can do to help a sale.
should be plenty of people that are desperate and want a cheapy radio that plays music through cd or aux. They might talk you down to 15-20 bucks though. Thats the going rate of 7+ years old head units.