customize payment

Hello I just bought the sitemile pricerr theme, but i need it customize for my needs. Atm when a customer pays for a product the money goes to our paypal account and when the customer mark the product as completed the 90% goes to seller and 10% for the site. The problem is that we have to report every sale to the state, when the money goes to our account and then to seller. This require a lot of adminstration/paper work. Thats why we need to customize the payment. What would it cost for u to customize the site, so when one buys the product, then a message will be sent to the seller and when he mark as delivered the buyer will have to mark as completed and then the money will be devided directly 10% to us and 90% to seller. So when the customer pays for the product the money will be on standby until the buyer press completed. Then the money will be transffered. Its very important that it will be integrated in the Sitemile theme. With this change, it means that some of the other function that was designed for the other system needs to be change/deleted to. Dont know if its possible to devide 90% to seller and 10% to us directly from the buyer but otherwise i would love to hear, some solutions, since we dont want the money to go through us. Since we will have to report that to the state everytime. Best regards.