Newegg offers the refurbished Netgear N900 802.11n Wireless Dual Band Wireless USB Adapter, model no. WNDA4100, for $11.99. This $10 mail-in rebate drops it to $1.99. With free shipping, that's $7 below last month's refurb mention and the lowest total price we've seen. (It's a current low for a refurb by $23.) It features data transfer rates of up to 450 MB/s. Rebate expires September 30.
A 1-year warranty applies, but it's unclear who backs it.