Hey now! That's great!
Luckily there are a LOT of wine/drinking related stamps and images.
I would suggest gift card holders too.
Do they have other cards there? Check their prices-that helps. I might ask them what they plan to sell them for and work backwards from there.
Ie if they can only charge 4 bucks then I am thinking single layer, CAS cards because they likely are not giving you more than 2.... If they are charging 10...you can do more. See what I mean?
Do they have an idea of what they want? Do they want simple or they want gussied up? They might be thinking for fancier than they have now?
Imho, You have to decide what how to value them once you know those things b/c it is personal. I never think we can get enough for a card so it becomes how much am I willing to give away my time?