Adorama offers the Samsung 50" 1080p Smart LED-Backlit LCD HD Television, model no. UN50H6203, for $547.99 with free shipping. (Fry's Electronics and ABT have it for the same price.) Aside from the mention below, that's the lowest total price we could find by $132 and tied as the lowest total price we've seen for a new Samsung 50" 1080p TV. It features 1920x1080 (1080p) native resolution, 120Hz refresh rate, two HDMI ports, two USB ports, WiFi, and Ethernet.
A close price: Best Buy sells this TV for $549.99 with free shipping.