Linksys via eBay offers its refurbished Linksys AC750 Dual-Band 802.11ac Wireless Range Extender for $17.99 with free shipping. That's $9 under our April refurb mention and $37 less than the lowest price we could find for a new one today. It features dual 2.4GHz and 5GHz bands, WPA/WPA2 encryption, Ethernet, and coverage up to 6,500 square feet.
Note: A 90-day Linksys warranty applies.