If history is any guide, the advent of the iPhone 4S will soon render the iPhone 4 both significantly less sexy and significantly less valuable on the resale market. But the good news for early adopters is that Apple will pay them up to $200 to buy back their mint-condition iPhone 4.
As The Next Web points out, Apple's Reuse and Recycling Program offers the money in the form of an Apple gift card--useful if you want to turn around and buy the 4S. All you have to do is go to the site, answer a few questions about the phone you're selling, and receive an estimate on the phone's resale price. After that, ship the phone to Apple, and receive your gift card shortly after. As of Tuesday afternoon, Apple was still willing to pay $180 for a gently used 16GB iPhone 4, and $200 for the 32GB model.
But that's for phones in pristine condition--the payout goes down for phones with scuffs, scratches, or water damage. Phones with dying batteries and without power cords also get a lower payout; you'll also want to clear the content and settings from the phone to achieve your best resale value.
Interestingly, the Reuse and Recycle Program site suggests you can also receive a $105 gift card if you sell Apple a top-condition 16GB iPhone 3GS; Apple will now give you an 8GB model of the same phone for free--provided you sign a two-year phone service contract. Penny-pinching iPhone fans might find the 3GS--both buying and selling--worth their while.