By Robert Schoon (r.schoon@latinospost.com) | First Posted: Sep 21, 2013 10:31 AM EDT

You can potentially get the iPhone 5s or iPhone 5c for free with a trade-in, as Wal-Mart is beginning its smartphone trade-in program on Saturday Sept. 21, one day after the two hot Apple smartphones hit the shelves.

Wal-Mart has already marked down the iPhone 5c to $79 with a two-year contract with AT&T, Verizon or Sprint. Additionally, the cheapest model of the iPhone 5s, the 16GB version, is priced down at $189, after Wal-Mart's $10 sale discount.

But that is the price for people who rushed Wal-Mart stores to buy the new Apple iPhones on Friday, September 20, the release date for the two iPhones. If you wait for Saturday (and hopefully there are still iPhone 5s's in stock, but that's a different topic), you can trade in your old smartphone for even more of a discount.

For example, when it launches the trade-in program on Saturday, the world's largest retailer will accept phones as old as the Samsung Galaxy S2, which is a smartphone from two years ago. And if you have a newer (non-damaged) phone like an iPhone 5, you can get a trade-in value of about $300. That's about $50 better than Apple's own trade-in program. Do the math. That means you can possibly get a brand new iPhone 5s, even the 32GB model, for nothing. Zilch. (With a two-year contract, of course.)

Of course, other retailers like AT&T, Verizon and even now Apple are accepting trade-ins, but if you have an older phone and want a new iPhone 5c or the base model iPhone 5s, your best bet may be Wal-Mart. That's because the retailer already can contract you out on those major carriers, and if you have an old phone worth less for trade-in, you'll also be able to stack the deals by taking advantage of Wal-Mart's already discounted prices.

The trade-in program starts Saturday Sept. 21, and while there are already lines for the new iPhone 5s and iPhone 5c, there will undoubtedly be more at Wal-Mart for the trade-in program and the new iPhones. 

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