newegg.com offers the Western Digital Scorpio Blue 2.5" 640GB Serial ATA Internal Notebook Hard Drive, model no. WD6400BEVT, bundled with the Western Digital Caviar Black 750GB Serial ATA 3Gb/s Internal Desktop Hard Drive, model no. WD7501AALS, for $154.99 with free shipping. That's $55 off and the lowest total price we could find for the pair by $30.    

Stock up and the price drops by $10 to $30, as seen here. For example, buy five of these combos for $624.95, or $124.99 each.