Affiliate Plugin that automates cheque writing for affiliates

I have a rather strange request from my client. He wants a way to automate the writing of business cheques for affiliates of our upcoming web site. The way the site is designed, we could potentially have thousands of affiliates that would participate by sending qualified traffic to the web site. Affiliates would then be paid via cheque each month from the company account.

The client doesn’t want the hassle of writing cheques by hand for reach of the affiliates that have earned income from the web site.

I assume one way I could do this is have the client export a CSV file from our chosen affiliate plugin, and then import that CSV file into a mail merge in Word? That would seem to me to be the easiest and most elegant solution. The next question then is, which affiliate plugin to use? We are currently implementing the Group Buying Plugin.

Does anyone have an Affiliate plugin they like best with all the features we are looking for? Tracking visits and sales through the Group Buying plugin?