Walmart offers the LG 50" 1080p LED-Backlit LCD HD Television, model no. 50LN5200, for $578 with free shipping. (Amazon charges the same.) That's the lowest total price we could find by $2, outside of the price below. It features a 1920x1080 (1080p) native resolution, LED backlight, USB, and two HDMI inputs.

A close price: Adorama has it for a buck more.