Western Digital WD Black WD5003AZEX 500GB Internal Hard Drive for $59.99 shipped after promo code EMCYTZT4867. Here is a screenshot for your 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. Most places have it for over $70.