Western Digital My Passport Ultra 3TB USB 3.0 Portable Hard Drive for $109.99 shipped. Here is a screenshot for reference. This portable USB drive does not require a separate power supply and is smaller than most of them, making it more convenient to carry around. USB 3.0 interface is compatible with USB 2.0 and able to transfer data at 3x faster by using USB 3.0. Most places have it for about $119.