Mwave offers the Sans Digital 4-Bay USB 3.0 Hardware RAID Enclosure for Mac, model no. MS4CT+, for $159.99 with free shipping. That's the lowest total price we could find by $28. It features five different RAID modes, hot-swappable slots, dust-free cover, adjustable cooling fan, eSATA, Firewire 400, and Firewire 800.