The folks at Apple will soon reveal a new iPhone, inevitably leaving some consumers looking at their current device while asking, “What did I ever see in you in the first place?” Walmart, however, still sees some value in that phone you don’t love anymore (especially in terms of its resale value on the secondary market — hubba hubba) and is willing to take it off your hands. But is it a good deal?

W-mart announced this morning that it will start accepting trade-ins on smartphones on Sept. 21 at both Walmart and Sam’s Club stores. Customers will get — in credit toward a new phone, not cash — anywhere from $50 to $300 for their devices, depending on the desirability and condition of each trade-in.

In a statement, the company gave some examples of what customers would get for their trade-in. At the high end is a “working, non-damaged” iPhone 5, which will earn $300 in credit. A Galaxy S3 in similar condition could score $175, while the Galaxy S2 gets little love, with only $52 in credit being offered for a device in relatively pristine condition. So if you have an S2 with a huge crack in the screen, don’t expect to get anything.

As mentioned, the big catch to this trade-in program is that you don’t get cash for your device. You don’t even get Walmart store credit. Instead, the trade-in value is applied to a new smartphone, one that comes with a two-year commitment to AT&T, Verizon Wireless, or Sprint (no T-Mobile). The only other option is to apply the trade-in value to a prepaid phone for use on Walmart’s Straight Talk system.

Why is Walmart doing this? Because many of us are fickle consumers who have little to no problem with ditching a perfectly good phone when the new one comes along. Meanwhile, there is an entire market in developing nations willing to pay nicely for secondhand smartphones. So Walmart gets the commission from the wireless providers on roping you into a new contract and it stands to make a pile of cash when these phones are sold on the secondary market.

There are numerous other retailers and services that will pay you actual money for your used phone, rather than just using the trade-in as a way to lock you into another contract. At least when you get cash for your phone, it’s up to you what to do with the money. So it always helps to shop your phone around first before just taking it over to a Walmart and trading it in.

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