With no contract required, CowBoom offers the used Apple iPhone 4 16GB for AT&T Wireless in Black, model no. MC608LL/A, for $299.99. Coupon code "HOLIDAY15" drops it to $254.99. With free shipping, that's $25 under last month's mention of a used one and the least expensive out-of-contract iPhone 4 we've ever seen. (It's also currently $214 less than a new one with no contract.) Sales tax is added where applicable. It features an Apple A4 processor, 326-ppi (pixel per inch) Retina 3.5" display running at 960x640, gyroscope, front- and rear-facing cameras, 5-megapixel camera with LED flash, 720p video capture at 30 fps, 802.11n wireless networking, dual microphones, and more.

Note that no warranty information is provided.