mwave offers the EnGenius 802.11n Wireless USB Adapter, model no. EUB-9706, for $15.99 with free shipping. That's $4 under our April mention and the lowest total price we've seen for a new one, although we've seen refurbs for as much as $6 less as recently as May. (It's also a current price low by $2.) It features WEP, WPA, and WPA2 encryption.