For its members, Sam's Club offers the Vizio SmartCast E-Series 49.5" 4K 2160p LED-Backlit LCD Ultra HD Smart Television, model no. E50U-D2, for $418 with free shipping. (Non-members pay an extra $41.38; a Sam's Club membership is just a few dollars more at $45.) That's the lowest total price we could find by $41 and the best standalone deal we've seen. It features a 3840x2160 (2160p) native resolution, full-array LED backlight, 802.11ac wireless, Chromecast, USB, and four HDMI inputs. Deal ends April 18..
Note: It lacks a tuner. You'll need to buy one separately to watch over-the-air broadcasts.