You need to charge rent if you are staying with the products and being responsible for them. I would not charge by percentage. When I had my craft/consignment store I charged all the crafters rent to put their stuff in the store and I was responsible for it. I kept up with what they sold and gave them their money. I got mine and they got theirs. That was about 6/7 yrs ago but that is the way everyone that I know does it. You take your part of the money before you pay them. Linda in Ga