eXpansys offers the refurbished Western Digital Caviar Green 1.5TB Serial ATA 3Gb/s Internal Hard Drive, model no. WD15EARS, for $44.99. With free shipping, that's $0.03/GB and $15 under the lowest total price we could find for a new one. This "green" 3.5" drive purportedly consumes less power compared to other models and features a 64MB cache.

Of note, no warranty information is provided.