Sans Digital TR4M+B TowerRAID 4-Bay eSATA Tower Storage Enclosure for $99.99 shipped.  Here is a screenshot for your reference.  It comes with RR622 RAID controller card, features four hot-swappable 3.5"drive bays with up to 12TB capacity and supports RAID 0, 1, 10, 5, 5+ spare, spanning and JBOD,  It usually goes for about $149.