So you want to upgrade to that powerful iPhone 4S do you now? I bet you thought about getting rid of your used iPhone 4 for some extra cash in order to help finance the upgrade. Apple wants your used iPhone and in exchange, it will send you an Apple Gift Card good towards goodies like the iPhone 4S. The thing is, Apple uses a third party service which will offer you next to nothing compared to what you can get for it if you sell your iPhone yourself using services like eBay. Just for an example, a mint condition 16GB iPhone 4 will only score you $180, and that's not enough. You will be able to get double than that right now if you sell it on your own and have enough to treat yourself to a nice iPhone 4S with enough storage to store all those 8-megapixel photos and 1080p videos! We highly recommend skipping the 16GB model if you're trigger happy.
Apple's Recycling Program may be a convenient route without having to think much, but a bit of minutes work setting up an eBay auction will help you get the most out of your lovely used iPhone 4.