TP-LINK 802.11n N300 Wireless Adapter for $15 + free shipping
Newegg offers the TP-LINK 802.11n N300 High Gain Wireless USB 2.0 Adapter, model no. TL-WN822N, for $18.99. Coupon code "EMCPBHA47" cuts it to $14.99. With free shipping, that's tied with our July mention and the lowest total price we could find by $4. It features dual 3dBi omni-directional antennas, a maximum data transfer rate of 300Mbps, and 64-bit/128-bit/152-bit WEP/WPA/WPA2/PSK support. Coupon expires September 1.
3 very similar deals were also reported by some other sources: