You do need to be sure you recover your cost to make them and then take into consideration the cost of renting a space at the craft show, too. You might try going to
www.etsy.com and searching for them there to see what people are charging. If you've never been to Etsy, it is a website where people sell handmade items.
I agree they would be perfect for a jacket zipper pull or to attach to a backpack zipper, too. I think I've also seen some advertised as to attach to a cell phone case. Yours look very nice! Good luck!!