Walmart offers the refurbished Sharp Aquos 55" 4K 2160p WiFi LED-Backlit LCD Smart Ultra HD Television, model no. LC-55UB30, for $549.99 with free shipping. That's tied with our mention from two weeks ago and $130 under the lowest price we could find for it new. It features a 3840x2160 (2160p) native resolution, 4K upscaling, 802.11n wireless, Ethernet, Smart TV apps (including Hulu Plus, Netflix, and YouTube), USB, and four HDMI inputs.
Note: No warranty information is provided.