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This can be a great way to recoup the cost of a new phone -- especially if you aren't eligible for an upgrade or are switching to another carrier.
The iPhone 5 announcement means that tons of older iPhone devices are about to hit the secondary market. As we've seen in the past, that flood of devices can lower the buyback amount companies are willing to pay for your device. If you're interested in selling your device to a buyback service, lock in now, rather than later.
[More from Mashable: Find Out If You’re Eligible for an iPhone 5 Upgrade]
We looked at what the most popular buyback services are paying for the iPhone 4S. As of 8:30 p.m. ET, this is what we found:
iPhone 4S 64GB, AT&T or Unlocked
The 64GB iPhone 4S is the most expensive model, and that's what we used to base our pricing on in this test.
The best offer we saw for the 64GB iPhone 4S is courtesy of eBay's Instant Sale.
Instant Sale will pay $400 for a working, fully functional 64GB iPhone 4S. The device needs to be fully functional, have no physical damage and include the charger.
The popular trade-in service Gazelle will pay $350 for a 64GB iPhone 4S on AT&T. Earlier today, Gazelle was offering $400 for the same unit, which means that trade-in volume is already impacting buyback offers.
Like Gazelle, NextWorth is offering $350 for a 64GB iPhone 4S-at&t/). The device needs to be working and cannot have a cracked display.
Amazon's Trade-In program will pay up to $391 on an Amazon gift card for a 64GB iPhone 4S. Amazon will actually pay $460 on a gift card for a "like new" iPhone 4S, but Amazon's requirements for what constitutes "like new" is stricter than most other companies. It needs the original packaging and should be presentable as a gift.
At Apple's Reuse and Recycle website, powered by PowerON, the company will offer a $345 gift card for a 64GB iPhone 4S.
Note: With the exception of Amazon and eBay Instant Sale, Sprint and Verizon iPhone 4S models go for significantly less than their AT&T counterparts.
The buyback price for other models will depend on carrier and location. eBay Instant Sale, at the time of this writing, is offering the highest cash buyback amounts for most phone models.
Amazon.com is offering a better buyback price for some models, however, users need to keep in mind that they will be paid with an Amazon gift card, not cash.
Gazelle, NextWorth and Apple all vary depending on when you lock in your deal and what model you are trading in.
A number of services are also offering good rates for iPhone 4 trade-ins.
Are you going to sell off your old iPhone? Let us know in the comments!
This story originally published on Mashable here.