NextWarehouse offers the Thecus 4-Bay External Network Storage Enclosure, model no. N4100PRO, for $339.06. With free shipping, that's $11 under our February mention and the lowest total price we could find by $11, outside the mention below. This Gigabit Ethernet NAS enclosure can hold four Serial ATA hard drives up to 4TB and supports RAID 0, 1, 5, 6, 10, and JBOD.

A close price is TigerDirect's $329.99 plus $9.56 for shipping.