Similar to reward points concept you can set supercash for individual products. So that when a customer makes a purchase he/she can be rewarded with supercash.

Here you can set supercash amount for products, search product by product name or product id. 

When you search by product name, replace spaces with +.. For example if you want to search macbook pro, enter macbook+pro in the search field

No email or alert is sent when you set supercash for the product.