I think you're getting trolled a bit, don't worry. I'd be confident they're legit. If they were fake they'd be £20 or something and you'd be able to tell.
I've spent more on sunglasses than I'd be happy to admit over the years (mostly Oakleys) but I managed to curb the spending, however I now blame you if it starts up again for posting that link![]()
The best way of selling fakes on the internet is to do them only slightly cheaper than the genuine ones. That way everybody thinks they must be genuine.........