Seagate 500GB 7200 RPM 16MB Cache SATA 3.0Gb/s 3.5″ Hard Drive $37.99

Newegg.com has the Seagate Barracuda 7200.12 ST3500418AS 500GB 7200 RPM 16MB Cache SATA 3.0Gb/s 3.5″ Internal Hard Drive for $37.99 with Free Shipping.