At Best Buy, trade in a used, fully-functional mobile phone and receive up to a $360 gift card. That's the largest credit offer we've seen for cell phone trade-ins at Best Buy this year. The credit value will be determined by the condition and model of the phone. As of this writing, a Samsung Galaxy IV (in good condition) will fetch you a $350 credit while an iPhone 5 64GB (in good condition) will yield a $360 credit. (Note, however, that Amazon may offer a slightly higher trade-in credit for the iPhone.) Some conditions may apply.