Auto generated PayPal script

I have master resale rights to many digital products. I have affiliates who would like to sell those products without having to create or host thier own sales pages. I need a way they can refer prospects to the sales site with an affiliate code, but when the propect cliks the buy button, the money goes to the AFFILIATEs paypal account (rather than into mine and I then I have to pay them). I am hosted on a dedicated unix server and have php/mysql installed