We first profiled the Western Digital MyBook Thunderbolt Duo at CES in January and noted the extraordinary speed of the drives, especially when daisy chained (above find 780MB/s read, 600+MB/s write). Today, Macrumors notes that Western Digital is making the drives available for $599 (4TB) and $699 (6TB).  While those prices are steep, they fall in line with new Thunderbolt parts across the line.

We’ve reviewed the much slower Firewire/USB Western Digital Studio 6TB drives and came away impressed. Those retail for around $430 currently ($270 less than the Thunderbolt version) but use energy efficient (read: slower) internal drives and slower Firewire 800 connectivity options.

Notably B&H Photo and Video is selling the Western Digital MyBook Thunderbolt Duo already with $50 discounts (6TB – $649, 4TB- $549) and tax only in New York but without solid shipping dates.