Idea

I asked about this in another thread and was advised to suggest it here. I sell stuff at trade shows and comic book shows. Most of my shirts are based on buttons I make and sell at these shows, so these are obviously people who would be interested in my shirts. Right now I am telling people to look up the shirts on Amazon, but what would really be helpful is to let people pay a deposit in person (say $5) and get a coupon from me that they can redeem online for $5 when they complete the purchase of one of my shirts. Obviously I can sell them an Amazon gift card but there's no guarantee they would use it for a shirt.