Walmart offers the refurbished Samsung 55" 4K 2160p WiFi LED-Backlit LCD Smart Ultra HD Television, model no. UN55HU6840FXZA, for $629.99 with free shipping. That's $30 under our mention of a refurb from July and the lowest total price we've seen for this TV. (It's currently $284 under the cost of a new one.) It features a 3840x2160 native resolution, LED backlight, WiFi, Smart TV apps (including Hulu Plus, Netflix, YouTube, and more), USB, and four HDMI inputs.
No warranty information is available.