Mobile1Pros (97.9% Positive feedback) via eBay offers the factory unlocked 16GB iPhone 6 Plus for $599.99 shipped. That’s the lowest we’ve seen for an unlocked unit. With the iPhone 6 Plus you get a 5.5-inch LED-backlit widescreen, an 8-megapixel iSight camera, A8 chip, and 1080p HD video recording.
Note: Unlocked cell phones are compatible with GSM carriers like AT&T and T-Mobile as well as with GSM SIM cards. Unlocked cell phones will not work with CDMA Carriers like Sprint, Verizon, Boost or Virgin.