Western Digital offers its factory-refurbished Western Digital 6TB My Book Thunderbolt Duo External Hard Drive, model no. WDBUSK0060JSL-NESN, for $349.99 with free shipping. That's $220 under the lowest total price we could find for a new unit. It's configurable for maximum speed (RAID 0), data protection/mirror mode (RAID 1), or individually in JBOD mode. A 6-month Western Digital warranty applies.