I was thinking about making them unlimited BUT make it so that once I or anyone else buys a card, we can't view the list until the next restock. Sure, there is a way to bypass this by trading the blank card onto other accounts, but that can be fixed by making the blank cards account/soul bound. The headgear itself isn't account/soul bound.
Edit: Something like that pvp voter npc. Once you vote, you can't access it anymore. The Kafra npc could say something like, "You already traded blank cards. Come back next restock"
