What is the process of costing in SAP?

What is the process for costing in SAP? I assume each material has to have a cost. Top-level of material will add all sub-component to final product. Is this right? Then it will be update the field planned price window in costing 2 of MM03 screen? Costing is a special topic for the SAP MM/SD consultants. You need to check with them your special case. Your scenario is one out of many possibilities but there are also pricelists, price from last procurement, average price etc… as well as bottom-up calculation compared to retrograde top-down prices …