Newegg offers the D-Link 802.11ac USB 2.0 Network Adapter, model no. DWA-171, for $27.74. Coupon code "EMCWHHD52" cuts it to $19.99. With free shipping, that's the lowest total price we could find by $8 and the lowest price we've seen for this adapter. It features WPS, WPA, and WPA2 security. Coupon expires December 28.