Walmart offers the Samsung 55" 4K HDR Flat LED Ultra HD Smart Television, model no. UN55NU6900, for $477.99 with free shipping. That's the lowest price we could find by $40, outside of the mention below. Features include:

3840x2160 (2160p) native resolution

HDR 10

Smart TV apps

2 HDMI inputs

A close price: Best Buy charges $479.99 with free shipping.