Western Digital offers the factory-refurbished Western Digital 4TB My Book Thunderbolt Duo External Hard Drive, model no. WDBUPB0040JSL-NESN, for $339.99 with free shipping. That's tied with our mention of a refurb from last week and the lowest total price we've seen for this model. (It's also $90 below the best price we could find for a new one.) It's configurable for maximum speed (RAID 0), data protection/mirror mode (RAID 1), or individually in JBOD mode. A 180-day Western Digital warranty applies.