TomTop offers the M8s+ / M8S Plus Kodi 8GB 4K 3D UHD WiFi Android TV Box for $42.84 plus $5.15 for shipping. (Choose "US Plug" and "US Warehouse" to see this deal.) That's $21 off list and the lowest total price we could find. Features include an Amlogic S812 1.8GHz quad-core CPU, 2GB RAM, 8GB hard drive, 4K support, WiFi, Ethernet, Android 5.1, HDMI, and two USB ports.
Note: The countdown timer on the product page does not reflect an actual expiration time and resets daily.