I think it's one of the maybe few things on their site that's inexplicably overpriced.
At my dry cleaner I saw the exact same thing for $2.00. (I know because I bought one from knitpicks for my mum for xmas the week before that.)
Exactly the same!
The owner said it is definitely worth it because it is kinder to delicate yarns than the shavers or the brushes or any of the other things, except maybe the sticky lint rollers, but those only metaphorically work.