All takes time, even just receiving the email from the customer, making sure the payment cleared and then generating the invoice to have someone pull the product off the shelf and put it in an envelope. Add up all the time for a small enterprise to do each step required for a sale. Then add in some extra time because not everything will go smoothly on each sale, payments not clearing, wrong address, handholding customers who can't find their ass from a hole in their head. Not saying $15 is fair, but I bet the total time to make a proper sale is probably 10 minutes of labor per order for a small company that doesn't have lot's of automation in place to sell things individually.