vendor evaluation cost of notification

Hi,

I am trying to set up vendor evaluation and want to take the cost of a notification into account. Std SAP allows me to assign an average cost to close a notification type. However the actual cost of closing a notificaiton from end to end could vary from notification to notification. Is there a better way to assign the actual cost of every notification for a vendor and use it in the quality score rather than using this average ? Something like using a QM order and booking the cost of every notificaiton on the QM order and then using that actual cost to score the vendor.

Thanks

GS