Hitachi 500GB Portable Hard Drive for $49.99 shipped after applying coupon code TX431R9QWX0735 and a $10 rebate. Here is a screenshot before the $10 rebate for your reference. It does not require a separate power supply and is also smaller, making it convenient to carry around. If asked during checkout, simply use your name as the business name. Most places have this drive for about $68 or more.