It's real.

From now until December 11, Radio Shack is slashing $50 off iPhone prices and unprecedented trade-in credits of up to $125 for a functional 3GS phone.

Combined, that $199 16GB iPhone 4 you've been waiting patiently for will cost you a mere $25.

As part of The Shack's Trade & Save program, existing iPhone users can receive $75 for their 3G model or $125 for the 3GS model. As long as the phone is functional and screen isn't cracked, you should be able to receive the full amount.

Meanwhile, the $50 instant savings off iPhones means that a $100 iPhone 3GS will cost you $50, a $199 16GB iPhone 4 will cost you $150, and a $300 32GB iPhone 4G costs $250. Combining both promotions to upgrade to an iPhone 4 costs $25, or free for the iPhone 3GS (plus the remaining balance of your trade-in value in store credit.)

AT&T customers can check out Radio Shacks' Eligibility Checker tool if you aren't sure. Furthermore, the deal is only available at The Shack's brick-and-mortar retail stores.

According to AppleInsider, which first discovered the promotion, Radio Shack is launching such a deal in order to "boost awareness of its wireless business and create an edge up on the competition."