Best Practice to Buy Service

Summary:

Hi

If requester want to buy service, such as Cutting Subcontractor for cutting 100 pieces (quantity) of steel. We want to create PR line with service item (with item number in PIM). If we create PR line with Goods or rate based service Line type, we cannot create work confirmation (receipt based on amount). If we create PR line with fixed price service, we cannot create PR line with quantity and we cannot create list price for specific category.

What is best practice to buy service with specific quantity, can be receipt based on amount, and we can create list price for specific PR line. We dont want the requester to set the amount to buy in PR.