Prob $200-250 honestly. Thats being pretty nice about it. Put it on Craigslist for $250, put pictures up of how it looks, people will try to low ball you whatever you put. So if you want $250, try $275. That's how I put stuff on there and sometime people bite for the price you put up. Having the Box and charging cord w/ Block makes a difference for some people too.
I don't believe in over pricing a product. I've usually listed and sold at to or at list price.
iPhone 4 16gb with box no charger. No headphone. Mint. It was my sisters she hadn't touched iPhone 4 since last October 2011 when she got the 4S. She had purchased iphone 4 April 2011.
Listed it for $250. Got $250 for it. Just list it at current market (selling price). Be firm.
I see ads posting iPhone 4 32GB for $350. Simply a joke since u can get a 32GB 4S for around that price.