Newegg offers the refurbished HGST Ultrastar A7K2000 2TB Serial ATA 3Gb/s 3.5" Internal Hard Drive, model no. HUA722020ALA331, for $38.99 with free shipping. That's $11 under the best deal we could find for a new one and the lowest total price we've seen for any 2TB 7200 rpm hard drive. It features a 32MB cache.

A 90-day warranty applies, but it's unclear who backs it. A close price: goHardDrive via Amazon has it for $39.99 with free shipping.