Member Store

I am looking to get a module created that will allow members to have a store on their profile where they can post media (pics vids ebooks etc) for sale. They post what they want to sale and then other members can purchase them from the store module and the member who sold it gets a credit in their account for sale price they set minus a 20% commission fee. We would need to tie this into the payment module that is used for memberships or something.