Walmart offers the refurbished Vizio 50" 4K 120Hz LED LCD Smart Ultra HD Television, model no. P502ui-B1E, for $399.99 with free shipping. That's $20 under our refurb mention from two weeks ago and the lowest price we've seen for this TV. (It's a current low for for a refurb by $200.) It features a 3840x2160 native resolution, 120Hz refresh rate, 2-sided remote with QWERTY keyboard, USB, and five HDMI inputs.
Note: No warranty information is provided.