What's the best way to get a new iPhone 5? Why, trade in your iPhone 4S and use the fruitful returns to upgrade your device, of course. Several services offer killer buyback programs, including Apple's Recycling Program, which gives you up to $330 for a used 32GB iPhone 4S. We surveyed several services, including Amazon, BuyBackWorld, eBay and Gazelle. Find out which one supplies the most coin for your used iPhone.