The BOM tabulates the item "quantity", and "cost center", the latter recorded with the part thru iProperties.
Is there a way to have Inventor multiply these together for an extended cost. I know I could manually enter the # but that will not change automatically, when the part count changes.
Wthout programming i think you will have to just do it in excel after you export your BOM.
You will likely have to do that bom as parts only, all levels.