Just got back from my local Tesco Extra store. I found several of these units on the shelf with a standard SEL sticker so it's not a store-specific offer or clearance line.
I've read a couple of reviews of it which sound mixed; apparently the device insists on reformatting the external HDs to its own format so you can't simply switch an HD back and forth between your PC and this unit. That puts me off, but this device might still be useful to some people especially for just £15.
Reviews here - http://fwd4.me/MGP