Walmart offers the Seiki 55" 4K 2160p LED LCD HD Television, model no. SE55UY04, for $599 with free shipping. That's the lowest total price we could find by $101 and the best we've seen for any 55" 4K TV, excluding credit offers. (We saw it with a $6 Shop Your Way Rewards credit for $1 more in February.) It features a 3840x2160 native resolution, 120Hz refresh rate, LED backlight, and three HDMI ports.

Update: The price has dropped to $579 with free shipping.