Mediasonic HUR3-SU3S3 2-Bay USB 3.0 and eSATA Raid Enclosure for $49.99 shipped.  Here is a screenshot for your reference.  It has a hardware embedded RAID controller to ensure data integrity with redundant back up capability, and supports single mode, JBOD mode, RAID 0 mode, and RAID 1 mode.  Most places have it for about $69.