Newegg offers the Asus 802.11n Wireless PCI Express Adapter, model no. PCE-N15, for $4.99 with free shipping via the steps below. That's the lowest total price we could find by $22. It features WEP, WPA, and WPA2 encryption. Deal ends April 8. To get this deal:

1. View the Asus 802.11n Wireless PCI Express Adapter for $29.99
2. apply coupon code "EMCARAN44" to cut the price to $14.99
3. redeem this $10 mail-in rebate for a final price of $4.99