The "standard" for craft shows is 3X the cost of materials. I never charge that for purses. I know I price mine too cheaply, but I enjoy making them. I figure if I cover the cost of materials plus a few extra $ I'm good. Of course, I'm not in it to really make money. I guess I would figure how long it would take to make and the cost of materials and then go from there. Once they find out just the cost of materials they may not want to pursue it.