Not 100% certain on this, but I don't think Rubik's ever sold these properly internationally. I know a few places where they can be bought online, but have never seen one in a shop in the UK.
The one I bought was an import from the original Mirror Blocks creator Hidetoshi Takegi.
To be perfectly honest, all the original ones have been stiff and inflexible. The best one I have is white plastic with black sparkly stickers. It has since sold out. I suggest you buy what you can and judge later. If Rubiks sold them here, I wouldn't say this. If they sold them in shops, I wouldn't say it either.
I can't point you at a rival shop, but I can say they're out there.
Please take off topic discussion off this forum. Thanks.