eBay has a pretty nice deal on the unlocked LG G3. They have the 2GB/16GB version going for $479, and the 3GB/32GB version is going for $589. Now these are both the unlocked D855 model and will work on both AT&T and T-Mobile here in the US. The LG G3 also features a 5.5-inch 2560x1440 resolution IPS display, Qualcomm Snapdragon 801 processor, 13MP camera with laser auto-focus and OIS+, as well as a 2MP front-facing camera and a 3000mAh battery inside.
LG G3 2GB/16GB - $479
LG G3 3GB/32GB - $589