I know they used to buy iPhones and pay you for them... Or atleast someone did. But if you sold your iPhone to them how much did they give you?
Or if you sold it to another place how much did you get for your iPhone 4?
Not very much, at all. You'll get more Craigslist.
I tried selling my iPhone 4s in various places. They'd all offer me $30 or less. F that. It was in perfect condition too. We decided to keep it and give it to DD. If you really want to sell it, I'd try eBay, Amazon or Craigslist.