There comes a time in every mobile user's life when a new phone that he or she simply must have hits the scene. The problem is, that scenario probably hits on a yearly basis (at the very least), and contracts are generally for a two-year term; that leaves no option but paying full-price for the new handset.

To help offset some of the cost of the new device, the most logical option is to sell the old one. That in itself poses another issue altogether: where to sell. There's always eBay and Craigslist, both of which have their own set of pros and cons; and then there are buy-back sites like uSell and Gazelle, both of which make users wait for their funds and don't normally offer the amount of money most people are looking for.