B&H Photo-Video offers the Western Digital 1TB My Passport Portable USB 2.0 Hard Drive for Mac, model no. WDBBXV0010BBK-NESN, for $96.49 with free shipping ($0.10/GB). That's the lowest total price we could find by $4. It connects and is powered via USB. Although it's formatted in HFS+ Journaled for Mac OS X, it can be reformatted for Windows computers.