Technology buyback programs, now offered by many major electronics retailers, offer a one-time fee at the time of purchase that will allow you to sell back your gadget later on.
However, you need to do your homework before you sign up and make sure that the program fits your needs. If you or your gadget recipient will be perfectly content with the technology for a long while, it may not be worth the extra cost. Your buyback credit will often come in the form of a retailer gift card, not cash.
Many programs also require original receipts, power cords and manuals to get the full value of the trade-in, and without them, you could be at a loss.
If you resell your mobile phone back to the retailer, the mobile service contract doesn't necessarily end. You will still get billed for the agreed-upon term, even if you've moved on to a new gadget and a new provider.
When you are ready to turn in your old gadget make sure it's wiped clean of personal data to avoid an identity compromise.