Hello.
When a product is received from supplier, supplier gives an invoice. On invoice there are prices for each item and also packaging/delivery cost. This cost adds value to each product according to its inital value. For example:
Item 1 price: 10$ (new value according to packaging: 11$)
Item 2 price: 20$ (new value according to packaging: 22$)
Packaging: 3$
Total sum: 33$