combine product discount

[freedo11]

I am wondering if there is a contribution for the following thing that I am needing. I sell some of my products in sets and I also list the products that are in the sets individually. I am needing a Create your own set option that would allow them to get a set amount off if they purchase several individual products. But the problem is, I want to be able to exclude my predesigned sets from the discount.

 

Is there any contributions that would do this?

 

Thanks,

Jonathan