Walmart offers the refurbished Samsung 54.6" 4K 2160p Curved LED-Backlit LCD Ultra HD Smart Television, model no. UN55KU6500, for $549 with free shipping. That's tied with our mention from last week as the best outright price we've seen in any condition. (It's also $151 under the lowest price we could find for a refurb today.) It features a 3840x2160 (2160p) native resolution, curved design, 802.11ac wireless, Bluetooth, Smart Hub apps (including Netflix, YouTube, and Hulu Plus), USB, and three HDMI ports.
A 90-day warranty applies, although it's unclear who backs it.