Oh I missed the Snuzzle one in the list! She is definitely pretty hard to come by as well, since most versions of her didn't come with a sticker. I want to say it was when she came with the parlour, but I would have to double check.
Most of Hathorcat's prices look spot on to me at the moment (my MB sticker was bough many years ago, as were my princess ones!) - the only ones I would say different for is Baby Lemondrop, who I would value at £10-12, and Baby Ribbon and Baby Lickety, who I would put at £15-20 maybe