Akodi via Amazon offers the Anewkodi AC600 Dual Band 802.11ac Wireless USB Adapter for $16.99. Coupon code "XTDRU68A" cuts it to $11.55. Plus, Prime members bag free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $8.06.) That's $5 under our July mention, $28 off list, and the lowest total price we could find. It features a long-range 2dBi antenna and up to 600MB/s WiFi speeds on 5GHz and 2.4GHz bands.