Newegg offers the refurbished D-Link 802.11n Wireless Range Extender, model no. DAP-1320, for $9.99 with free shipping. That's $5 under our mention of a refurb from September and the lowest total price we've seen in any condition. (It's also $10 under the best price we could find for a new unit.) It delivers up to 300Mbps for whole-home coverage.
A 90-day warranty applies, although it is unclear who backs it.