AutleyDirect via Amazon offers its Autley AW600 802.11ac Dual-Band Wireless USB Network Adapter for $17.99. Coupon code "KCZPUKA3" cuts it to $10.99. Plus, Prime members bag free shipping. That's within cents of our mention from a month ago and the lowest price we could find for a U.S.-based seller by a buck. It features a detachable 2dBi long-range antenna and wireless transmission speeds of up to 600Mb/s on 5GHz and 2.4GHz bands.
Don't mind waiting on your deal? Focus-Shopping via eBay offers a similar item for $9.99 with free shipping. Note that it ships from Hong Kong and requires two to four weeks for delivery.