We don't really have a reliable way to do that with our existing affiliate system, but you might consider setting up each product with the Multiple Emails method for our Integration feature, so the provider of each product would at least receive a notification when their item(s) are sold:
http://www.e-junkie.com/ej/tips.integration.built-in.htm#emails
Every month or quarter or whatever period you wish, you can use your Transaction Log to view sales for each product during that period. You can select any product along with the date range to view sales totals and details for just that product, or you can view your whole log for that period and download that log view to a file that you can open in any spreadsheet program like Excel to calculate totals -- e.g., you could sort rows by the Item Number field to group together all sales for each item and calculate sums easily from there.
