As one of its daily deals, 1Sale offers the TP-LINK 802.11n 300Mbps Wireless-N USB Adapter, model no. TL-WN821N, for $9.99 with free shipping. That's $10 under the lowest total price we could find elsewhere and the lowest price we've ever seen. This USB adapter features up to 300Mbps transfer speeds. Deal ends today.
Note that this item has an estimated delivery time of two to three weeks.