As one of its daily deals, CowBoom offers the 6.3-oz. Western Digital My Passport 640GB Portable USB External Hard Drive, model no. WDBAAA6400ABK-NESN, for $49.99 plus $5 for shipping ($0.09/GB). That's the lowest total price we could find by $26. Sales tax is added where applicable. It features password protection and 256-bit encryption. Deal ends today.