I am helping a startup business to launch and I will be building or finding a shopping cart software for its website. There will only be one product for sale, but anytime someone buys a product, I have to use customer information like their zipcode and which distributor they bought from to calculate commissions that will go to the different distributors. All the incoming money will be sent to one sort of escrow account for a few weeks, and after that few weeks is over, I need to be able to "throw the switch" and cause each of the 20,000 distributors to get their rightful share of that escrow account, depending on the data stored that reflects their sales activity and commissions due. Is this something I can write a script to handle? Better yet, is this something an inexpensive or open source solution can handle, or something that can be setup in something like Paypal? Or is a better approach to somehow create a webpage where each distributor can login to and see their commissions due and initiate the account transfer on their own, but the web app restrict them from transferring more than what they're due?

Thanks