Linksys offers its refurbished
Linksys AC1200 802.11ac Wireless Dual-Band Max Range Extender for
$29.99 with
free shipping. That's tied with last month's mention as the lowest price we've seen for it in any condition. (It's also at least $49 less than you'd pay for a new one.) It simultaneously extends ranges for 2.4GHz and 5GHz bands up to 10,000 sq. ft. and features four Gigabit Ethernet ports, a 3.5mm audio jack, and support for up to 128-bit encryption.
Note: A 90-day Linksys warranty applies.