mwave offers the refurbished Seagate Barracuda 160GB Serial ATA 6Gb/s Internal Hard Drive, model no. ST3160815AS, for $39.95 with free shipping ($0.25/GB). Outside of the price below, that's the lowest total price we could find for a refurb by $16. It runs at 7200 rpm and features an 8MB cache. A 60-day warranty applies, although it's unclear who backs it.

A close price: newegg has it for $39.99 with free shipping. It carries a 90-day warranty of unknown provenance.