[Exhibitman]

I would not go with # known as the key determinant of rarity because I don't see a hard cut-off as anything more than random: is 9 rare but 11 is not? Why, other than a round number bias?

I'd rather look to frequency of transactions in the card. With the tsunami of cards out there for sale every year, a card that transacts only a few times a year or less is what I would see as a rare card.

As for sales listings proclaiming a card as rare, that's just sales jackassery.