Before browsing the options, take a moment to identify the condition, features, and model of the swappable iPhone. This will help determine its potential value, because most online programs use a survey to calculate the iPhone’s estimate. Moreover, it is prudent to act now, as retailers will likely drop their prices as the launch date draws nearer.

Check out the top 10 trade-ins list below.

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  1. eBay: eBay is one of the first—and probably the most prominent— online garage sales, so it would make sense for the e-commerce service to provide a respected trade-in program with dough dispensed through PayPal. eBay advertises free shipping and gives quotes right away, but real values tend to début shy of the example quotes after determining the device’s condition online. A perfect iPhone 4 8GB (Black) – C Spire gets $139, where as the iPhone 4S 64GB (White) – AT&T banks $381.

  2. GameStop: GameStop is a bit more troublesome, because folks need to visit a physical store to swap an iPhone. A store associate will examine the smartphone and then offer cash or store credit for an exchange. Fortunately, through this method, the shipping is no longer a headache. Listed “up to trade-in” quotes start at $180 for an iPhone 4 8GB (Black) – Verizon, and they reach $345 for an iPhone 4S 64GB (White) – AT&T.

  3. Best Buy: BestBuy is one of the more simple services for swapping an Apple iPhone. Simply select the model, choose its quality, and add it to the cart. The retailer warned that actual trade-ins would vary according to condition, accessories, and other factors. A “perfect” iPhone 4 16 GB (White) divvies $162, where as an iPhone 4S 64GB (Black) in the same condition fetches $336.

  4. RadioShack: RadioShack touts in-store and online options for exchanging an iPhone. In fine print on the bottom of the website, however, the retailer notifies consumers that trade-ins are subject to applicable processing fees and must include chargers, cables or other accessories. The iPhone 4 8GB (Black) – C Spire is valued at $129, while an iPhone 4S 32GB (Black) – C Spire gets $220. There is probably one a few blocks from your house too.

  5. Apple’s Recycling Program: Apple’s Recycling Program issues an Apple Gift Card by mail, which works at any Apple Retail Store or the Apple Online Store, when swapping an iPhone. The tech giant offers $170 for an iPhone 4 16GB (Black). It also allots $345 for an iPhone 4S 64GB (White). The company even grants free shipping and packaging for the trade-in process generated by PowerOn.

  6. PowerMax: PowerMax does not show quotes on the website. It has a questionnaire about the smartphone and then contacts prospective traders within minutes. “By trading in, you have a seamless transaction with the trusted folks at PowerMax, who have done this for nearly two decades. It’s quick, it’s easy, and it’s secure,” contends the e-commerce service. PowerMax advertises that consumers can receive a check or credit for the agreed-upon amount, but a response e-mail from the website indicated it only permits trades for store credit and the exchange process takes four to six weeks.

  7. Craigslist: This is not a trade-in program, but it is still a feasible option. It is easy to quickly post the specs of a smartphone with a desired asking price. It is also free to post, but some may whine over the packaging and shipping hassle—hence its No. 10 spot on this list. Nevertheless, Craigslist is a popular website perfectly capable of matchmaking sellers to potential buyers.

  8. Verizon Wireless: The Verizon Wireless Trade-In Program accepts used Apple devices from any carrier. In just four simple steps, folks can determine the value of their iPhone and receive a Verizon Wireless electronic gift card via e-mail. The iPhone 4 16GB – AT&T, for instance, gets $140, while the iPhone 4S 64GB – Sprint earns $312.

  9. Glyde: While Glyde does not have a typical trade-in program, it does make it easy for consumers to buy and sell used electronics. It essentially provides consumers with “unique insight into the resale market for used electronics.” For instance, Glyde said used AT&T iPhone models sell for higher prices than Verizon models. It can also give up-to-date and accurate pricing for old iPhone models with trend and geographical data. Glyde even offers an iPhone Upgrade tool, so consumers can determine how much their new device will cost by selling their old one, as well as additional tips and advice on the best time to sell old smartphones to make the most money.

Please remember that quoted values are subject to change.