Amazon Marketplace clone for oscommerce store

Hi We have an oscommerce store, that we would like to add the option for people to create seller accounts, and then able to sell items on our site provided we have the item for sale ourself, PLEASE SEE AMAZON Marketplace for the idea of the thing we need. When a seller lists an item for sale, they must pay 10p per paypal per item they list. When the item sells they must be given an invoice to pay of 10% of the final selling price this again must be paid via paypal. If a customer adds a product that we sell and a product a seller has for sale they must be presented with our checkout and also a checkout to pay for the sellers item - this must be paid for via paypal only. Any questions please ask, but if you take a look at amazon you will see what we need. Please only bid if you have knowledge and can prove you have knowledge of oscommerce