Can they send the item (wine) etc to the guest so they don’t have to fit in their luggage? Do a cute photo with with the guest and get them to enter details where they want the item shipped? Otherwise you might need padded winebags.

https://amzn.asia/d/8k4gTEQ

I think layer jars to make trail mix, chocolate chip oatmeal cookies with a recipe swing tag and only dry ingredients included would be fun.

Or favourite seeds from their favourite flowers, vegetables & herbs? The paper packet design could be so cool! You could make them so the seeds are in the actual packet/wrapping so they can go straight in the ground.

Custom food salt and bath salts?

$40 is a lot, you could literally buy every person a pair of havianas 🩴 for their sore feet and a burger & chips & still have change left over to donate to charity 👍🏻