As usual, Walmart is trying to outdo its competitors with surprisingly low prices. Their latest target is Apple's iPhone 5s and iPhone 5c, which will be released Sept. 20.

Yesterday, it was reported that the iPhone 5s would be available with a two-year mobile contract at $199 for 16GB of memory, $299 for 32 GB and $399 for 64 GB. The iPhone 5c is will be available for $99 for 16 GB of memory and $199 for 32 GB. Again, these prices are contingent upon a two-year contract.

Walmart, however, has different plans.

On Thursday, the mega-chain superstore announced that they would sell the 16 GB iPhone 5s for $189, which is $10 less than the retail price. The 16 GB iPhone 5c will be sold for $79, $20 less than the full price. These deals require a two-year wireless contract as well.

In addition, Walmart is giving smartphone customers the opportunity for even more savings.

Beginning Sept. 21, customers can bring in their old smartphone and receive money toward the iPhone 5s or iPhone 5c. Credits range from $50 to $300, depending on the make, model and condition of the phone.

An iPhone 5 in working condition earns $300 in credit. Meanwhile, a customer with Samsung Galaxy S3 gets back $175 and customers trading in a Galaxy S2 receives $52.

"Smartphones have become a part of our customers' everyday lives and as new devices launch more frequently, trade-in programs are becoming more popular," Steve Bratspies, Walmart executive VP of general merchandise, said in a statement. "More and more, customers are choosing where they purchase new smartphones based on where they'll get the best value for their trade-ins."

This deal is available at Walmart and Sam's Club, Walmart's sister store.

Starting today, the iPhone 5c will be available for preorder at Walmart. Preorders are first-come, first-served. Those who preorder an iPhone 5c must retrieve their phone by Sept. 25 before Walmart is free to sell the device to someone else.

The iPhone 5s is not available for preorder.

Older versions of the iPhone will enjoy a price cut at Walmart stores as well. The 16 GB iPhone 5 will go from $98 to $79. The iPhone 4s, with either 8 GB or 16 GB, is priced at a mere 97 cents.  Walmart is even giving away money for iPhone lovers willing to buy the older iPhone 4. Starting Sept. 16, the phone will be sold for only 10 cents and will come with a $100 Walmart gift card. These prices require a two-year mobile contract.

Customers who are not interested in a wireless contract can still purchase iPhone's older models though Walmart's Straight Talk prepaid plan. This plan prices the iPhone 5 at $549 and the iPhone 4 at $349. These prices reflect a new $100 price drop and are available starting tomorrow.