Best Buy via eBay offers the LG 49" 4K 2160p WiFi LED-Backlit LCD Ultra HD Smart Television, model no. 49UF6430, for $499.99 with free shipping. (Amazon and P.C. Richard & Son have similar prices.) That's the lowest total price we could find by $199. It features a 3840x2160 (4K) native resolution, WiFi, webOS 2.0 Smart TV system, USB, and three HDMI inputs.
Update: Best Buy is now sold out; however, Amazon offers it for $497.99 with free shipping P.C. Richard & Son offers it for a buck more.