Wholesale Connection via eBay offers the refurbished TCL 55" 4K 2160p Flat LED-Backlit Ultra HD Roku Smart Television, model no. 55P607, for $429.80 with free shipping. That's $20 under the lowest price we could find for a refurb, outside of other eBay sellers. Features:

3840x2160 (2160p) native resolution

Content streaming via Roku TV (Netflix, Youtube, Hulu Plus, more)

802.11ac wireless

3 HDMI inputs, USB

Note that no warranty information is mentioned.