Newegg has the BELKIN F5D9050 IEEE 802.11b/g USB 2.0 Wireless G Plus MIMO Network Adapter for $13 with free shipping.
Specs:
* Standards: IEEE 802.11b/g
* Wireless Data Rates: Up to 54Mbps
* Security: 64/128-Bit WEP, WPA, WPA2
* WPA/WPA2: WPA2
* Antenna: Internal Antenna
* Operating Range: up to 1,000 ft.
* System Requirements: Windows 2000, XP, or Vista PC running Windows 2000, XP, or Vista PC with available USB Port
* Windows Vista: Certified for Windows Vista
* Model #: F5D9050
Newegg.com - BELKIN F5D9050 IEEE 802.11b/g USB 2.0 Wireless G Plus MIMO Network Adapter Up to 54Mbps Wireless Data Rates 64/128-Bit WEP, WPA, WPA2 - Wireless Adapters
BELKIN F5D9050 IEEE 802.11b/g USB 2.0 Wireless G Plus MIMO Network Adapter $13 + FS 
