At long last and well overdue the WD 5TB Red HDD is now starting to be listed, and this is backed up by the anecdotal evidence of the 4TB HDD's dropping in price a little.
WD50EFRX
http://www.broadbandbuyer.co.uk/shop/Sh ... 31&t=507#TI have been waiting for this to happen for some time, it now looks like it will happen soon
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Update (21-07-2014), the 6TB WD Red HDD has been launched as well, and ironically the 6TB HDD is in stock at Newegg Canada whilst the 5TB is still missing.
Better news still, judging by the pricing, the 6TB HDD is just as affordable per GB as the 5TB model, which is of course a serious advantage over what is usually expected of a price premium of 15-25%
Here is AnandTech's review (does not include all of the data for other drives tested, but you cant afford those anyway

).
http://www.anandtech.com/show/8263/6-tb ... ec-hgst-heAnd here is the prices at Newegg (21-07-2014)
http://www.newegg.com/Product/ProductLi ... LJPEHHSZQTAnd if you wonder why you cant see their prices, they have likely removed them (standard procedure for items out of stock with no current resupply date).
I hope to see these available the other side of the Atlantic soon, especially with the prices listed, the 6TB looks like a sweek offering with exactly the same cost per TB s th 5TB model and not much more than the new sweet-spot of the 3-4TB models.
Andy