Bestbuy offers WD - easystore 20TB External USB 3.0 Hard Drive - Black for $249.99 (orig. $449.99) with free shipping.

Product Description:
Back up important files securely with this black WD easystore desktop hard drive. The 20TB capacity provides ample space for archives and videos, while the USB 3.0 connectivity provides broad compatibility with most Windows and Mac devices. This WD easystore desktop hard drive features plug-and-play functionality for a quick, simple setup. 

• USB 3.0 interface
  Enables easy-to-use connection to devices. Backward compatible with USB 2.0 for simple connection to your computer.
• Rapid response
  Offers data transfer rates up to 5 Gbps in the USB 3.0 mode and 480 Mbps in the USB 2.0 mode.
• Easy-to-use auto backup
  Comes with the WD Discovery backup software that lets you set hourly, daily, or monthly backup schedules and makes it easy to back up high-capacity files to your drive.
• Compatible with PC and Mac*
  For use with your existing computers.
• 20TB storage capacity
  Provides ample space for storing documents, photos, music and more.
• Limited warranty
  This portable hard drive comes with a two-year warranty.
• External design
  The desktop storage features a USB cable and AC adapter, which makes it possible to work with most systems.
• Backup software**
  Allows you to manage your WD portable hard drive and expands its capabilities.