Hello, i am a vtiger crm expert with years of experience in installing and customizing the CRM system. I have worked on different custom modules and one that is about your requirements. It does something like this: you set different objectives for one or more users on the crm for the Opportunites, Sales Order and Invoice module, and for these modules you will set objectives based on products, organizations, totals etc and can input different conditions, so you will always know how your sales people are performing. The price for this module can always be arranged.
Feel free to ask me anything.
Best Regards,
Ardi