Ending today, newegg offers the Rosewill 802.11n USB Wireless Adapter, model no. RNX-N600UBE, for $27.99. Coupon code "EMCYTZT3627" cuts it to $19.99. With free shipping, that's the lowest total price we could find by $8. It's compatible with 2.4GHz and 5GHz wireless signals and capable of speeds up to 300Mbps.