Now through Saturday, retailer GameStop is running a promotion that nets customers an extra $50 toward the purchase of a new Xbox 360 with Kinect when trading in any iPod Touch, iPhone, or iPad device at its US locations. Additionally, trading in one of 15 select iPhone or iPad models will completely cover the cost of a brand new Xbox 360 with Kinect, which retails for $299.99.

According to the fine print, there’s one small caveat: the offer is only open to those enrolled in the company’s Power Up Rewards program, which is $14.99 a year. If you’ve got an unused Apple device laying around this isn’t a shabby deal. For details on what iPhone and iPad models are applicable, hit the break.

Example applies only when select iPhone and iPad models [iPad® 64GB WiFi, iPad® 64GB WiFi & 3G, iPad 2® (WiFi) 16GB, iPad 2® (WiFi) 32 GB, iPad 2® (WiFi) 64GB, iPad 2® (3G AT&T®) 16GB, iPad 2® (3G AT&T®) 32GB, iPad 2® (3G AT&T®) 64GB, iPad 2® (3G Verizon®) 16GB, iPad 2® (3G Verizon®) 32GB, iPad 2® (3G Verizon®) 64GB, iPhone 4S® 16GB (AT&T®), iPhone 4S® 32GB (AT&T®), iPhone 4S® 64GB (AT&T®), iPhone 4S® 64GB (Verizon®), iPhone 4S® 64GB (Sprint®)] are traded toward the purchase of a new Xbox 360 4GB with Kinect system bundle, regularly priced at $299.99.

Disclosure: GameStop sent us a $150 gift card for helping spread word of this promotion.

Follow this author on Twitter.