eBay with Newegg has the Seagate Backup STDT5000100 Plus 5TB USB 3.0 Desktop External USB 3.0/2.0 Hard Drive for $130 with free shipping. Features auto backup from social networking, mobile backup app and preloaded NTFS driver for Mac.
http://www.ebay.com/itm/301380770152
http://www.ebay.com/itm/301380770152