I am hoping to sell my black, 16gb iphone 4S (AT&T) in order to pay for the newly announced iPhone 5. I have had the phone for 10 months. It's in pretty good condition, with only a small scratch on the back plate of the phone. I have all original packaging, as well as usb cable, power adapter and earbuds. How much should I sell this phone for? Should I risk placing the phone on eBay as an auction? Does anybody have advice on the best way to sell this phone and get the most value out of it? Thanks!