This deal has ended.
Buy.com has the Edge DiskGO! 500GB 480Mbps USB 2.0 External Hard Drive on sale for just $119.99. It's compatible with both PC and Mac, and comes with a one-year warranty. Shipping is free, there is no sales tax (except CA, MA, MD, TN), and new Google Checkout users can get a $10 discount for signing up.