My local coffee shop in Ogaki will sell you 11 200 yen vouchers (conveniently equal to one cup of coffee) for 2,000 yen. How precisely does Bitcoin improve this for buyer or seller?
But you might want to give some thought to how you'll prevent counterfeiting. A voucher for a cup of coffee is one thing, but if you want to raise a lot of money then security is a bigger concern. As far as I know there's no established infrastructure or service for this sort of thing. If you do it, you're pretty much building something from scratch.
Bitcoin has the potential to make it as simple as installing client software, and telling your customer base about it. If bitcoin gets to common usage, and people succeed in building decentralized exchanges, then your customers could buy your vouchers using the app they use already, and resell them later with a button click or two.