Western Digital WD Blue WD10EZEX 1TB Internal Hard Drive for $39.99 shipped. Here is a screenshot for reference. It features 7200 RPM, 64MB cache, and uses SATA 6.0Gb/s interface. Note that it comes in OEM packaging, which means no pretty retail box but is otherwise identical.
This deal has expired as it is now out of stock. Congratulations to those able to get in on it.