Big Deals via eBay offers the refurbished Netgear RangeMax Dual Band 802.11n Wireless USB 2.0 Adapter, model no. WNDA3100v2, for $10.49 with free shipping. That's the lowest total price we could find for a refurbished model by $5. This adapter works on both 2.4GHz and 5GHz networks and features data rates of up to 600Mbps.
A warranty card is included, although it's unclear who backs it and for how long.