Western Digital offers the factory-refurbished Western Digital 4TB My Book Thunderbolt Duo External Hard Drive, model no. WDBUPB0040JSL-NESN, for $299.99 with free shipping. That's tied with our mention from last month and $382 under the lowest total price we could find for a refurb 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.