Newegg has the BELKIN F5D8013 N Wireless Notebook Card for $20 with free shipping.
Specs:
* Type: 802.11b/g/n CardBus Wireless Adapter
* Standards: IEEE 802.11b, IEEE 802.11g, IEEE 802.11n draft
* Max Data Rates: 300Mbps
* Interface: 32bit CardBus
* Distance: Typical Operating Range: Up to 1,200 ft. (365.8m) Wireless performance may vary depending on the networking environment
* Humidity: Max. 95% (non-condensing)
* Temperature: 0ºC to 60ºC
* System Requirements: PC-compatible computer with one available 32-bit, CardBus slot Windows 2000, XP with SP2, or Vista (clients are not Mac OS compatible) Minimum 64MB of RAM CD-ROM drive Internet browser
* Model #: F5D8013
Newegg.com - BELKIN F5D8013 N Wireless Notebook Card - Laptop Networking
BELKIN F5D8013 N Wireless Notebook Card (Cardbus) $20 + FS 
