newegg offers the Buffalo MiniStation Stealth 500GB USB 2.0 Portable External Hard Drive in Black, model no. HD-PCT500U2/B, for $49.99 with free shipping ($0.10/GB). (Buy.com via Rakuten Shopping and Amazon charge the same.) That's tied with our February mention as the lowest total price we've seen in over a year. (It's a current price low by $4.) This portable hard drive is Mac- and Windows-compatible.