Best Buy has a new iPhone trade-in deal that can't be beat‚ but it only lasts until Mother's Day [1], Sunday, May 11. For starters, both the iPhone 5C and 5S are 50 percent off at Best Buy [2] stores. This means that the candy-colored iPhone 5C [3] is down to $50 and the fingerprint-sensing iPhone 5S [4] is $100 with a two-year contract on Sprint and Verizon only (no T-Mobile or AT&T, sorry).

But the real deal lies in Best Buy's updated trade-in program [5], which will now pay out more for your old iPhones. The devices must be in good working condition, and you must complete the trade in stores.

• iPhone 5 = $200 back
• iPhone 4S = $150 back
• iPhone 4 = $100 back

At the current iPhone 5S price of $100, you could upgrade an iPhone 4 to an iPhone 5S . . . for free!