Data Robotics Drobo 4-Bay USB 2.0/FireWire SATA Storage Array DR04DD10 for $319.99 shipped after a $25 rebate.  Here is a screenshot for your reference.  Alternatively, it is available at Newegg for the same price shipped after the same rebate.  This is a fairly fancy data backup solution for the technically inclined, and yet it is also user-friendly relative to all its features.  More information about this backup device can be found here, along with a review for your reference.  Most places have it for about $399.