Newegg offers the ASUS 802.11n Wireless PCI Express Adapter, model no. PCE-N10, for $3.99 with free shipping via the directions below. That's tied with last month's mention as the best price we've seen. (It's a current low by $7.) It features WEP, WPA, and WPA2 encryption. Rebate expires April 30. To get this deal:

1. View the ASUS 802.11n Wireless PCI Express Adapter for $21.99
2. apply coupon code "EMCETGM36" to drop the price to $13.99
3. redeem this $10 mail-in rebate for a final price of $3.99