Trade-in special from RadioShack slashes up to $200 off the iPhone 4
Any iPhone 3GS should do, as long as it is in working condition and has not suffered from any water or heavy physical damage. In return, RadioShack promises to sell you a brand new iPhone 4 with at least $100 slashed off its price. We suppose that the discount amount varies depending on the condition of the device being returned, just like it is with the rest of the Shack's trade-in specials. The maximum discount that you can hope for is $200, which is exactly what the 16GB iPhone 4 retails for, and before you go, it would probably be a good idea to check quotes from other used cellphone dealers as well.