Newegg offers the refurbished ASUS 802.11ac Wireless Dual-Band Gigabit Router, model no. RT-AC68R, for $99.99 with free shipping. That's $48 under our mention of a new model from last October and the lowest total price we've seen in any condition. (It's $66 under a new one today.) It features data transfer rates of up to 1,300Mbps and USB 3.0.
A 90-day warranty applies, although it's unclear who backs it.