On Monday, Best Buy announced a one day sale (Aug. 22) offering Apple’s 8GB iPhone 3GS for free.

Of course, it’s not entirely free. In order to receive a free iPhone 3GS, customers must sign a new or upgraded two-year contract with AT&T.

The iPhone 3GS is listed for $50 on Apple’s website. The iPhone 3GS lacks the Retina Display of the iPhone 4, has a slower processor and lacks a forward-facing camera for Facetime video calls. The iPhone 3GS features 256MB of RAM, a 600MHz CPU, 3-MP camera and video camera, and a 480 by 320 pixel display.

According to reports, Best Buy is promoting this offer to make way for the soon to be released iPhone 5.

The iPhone 3GS is currently available in Best Buy and Best Buy Mobile stores.