Seagate STAY3000102 Expansion 3TB USB 3.0 External Drive for $129.99 shipped.  Here is a screenshot for reference.  It features plug-and-play with no software to install, built-in power management, and more.  Note that it also has USB 3.0 for faster transfer speed while maintaining compatibiility with USB 2.0.  Most places have it for about $149.