Walmart offers the refurbished Vizio 50" 4K 120Hz LED LCD Ultra HD Smart Television, model no. P502ui-B1E, for $299.99 with free shipping. That's $117 under our March refurb mention and one of the least expensive 50" 4K Smart TVs we've seen. (It's the best deal today by $110.) It features a full-array LED backlight, 120Hz refresh rate, 2-sided remote with QWERTY keyboard, Smart TV apps (including Netflix, Amazon, and Hulu Plus), USB, and five HDMI inputs.
Note: a 90-day warranty applies but it's unclear who backs it.