With activation of a 2-year contract, T-Mobile offers the Apple iPhone 6 64GB Smartphone for Space Gray, Silver, or Gold for $649.92 (which you will have to pay in 24 monthly payments of $27.08). With free shipping, that's $99 under the lowest total price we could find for an unlocked T-mobile model elsewhere. It features an Apple A8 processor, 4.7" 1334x750 Retina display, 8-megapixel iSight camera, and 1080p video capture with 60 fps video shooting (240 fps shooting at 720p slow motion playback), 1.2-megapixel FaceTime HD camera, 802.11n wireless, and Bluetooth 4.0.

Note: A $10 activation fee applies.