Newegg offers the TRENDnet 802.11n Mini Wireless USB Adapter, model no. TEW-648UB, for $9.99 with free shipping. (Amazon charges the same.) That's tied with our mention from last summer and the lowest total price we could find by a buck. It features transfer rates up to 150Mbps and support for WEP, WPA/WPA2-RADIUS, and WPA-PSK/WPA2-PSK encryption.

Update: It's now out of stock at Newegg; however, Amazon still offers it for $9.99 with free shipping.