bonus system for virtuemart

[Magican-Gothic]

Hello,
i´m looking for a bonus system like Alphauserpoint for virtuemart. There are solutions for CB or lockin, but i could not find something that works with virtuemart.
The idea is: They shopper got  x points for his paid cart in virtuemart and could spend it in a separate virtuemart categorie with bonus-products during one of his next shopping tour, of if he collected enough points for a bonus product.

Did anybody knows a solution for that?

Kind regards