Newegg offers the refurbished Asus Dual Band 802.11ac / 802.11n Wireless 1750 Gigabit Router, model no. RT-AC66R, for $129.99. Coupon code "EMCANNN22" cuts it to $89.99. With free shipping, that's tied with our mention of a refurb from last month as the best price we've seen for this model. (It's also $40 under the best price we could find for a new unit.) It features a maximum speed of 1.75Gbps, dual-band support, four Gigabit Ethernet ports, and two USB ports.
A 90-day warranty applies, but it is unclear who backs it.