I'm hoping there is because when the iPhone 4 came out, I sold my 3GS for $300 (was gone in 4 hours) and still had to get another 2 year contract to buy the new one for $300.
EDIT: Oh wow, and iPhone 4's don't seem to be worth that much anymore
http://philadelphia.craigslist.org/ele/2541833286.html
EDIT: Oh wow, and iPhone 4's don't seem to be worth that much anymore
http://philadelphia.craigslist.org/ele/2541833286.html