The costs of both materials and wages must always be taken into consideration ...

Eine Frage: bei "Warenkosten" geht es um die Kosten von Rohmaterialien? Wenn ja, so

"The cost of raw materials and wages must always be considered together, especially when comparing one's own factory to others."

Aber "Waren" sind doch keine "raw materials," oder? Das sind eher "products," glaube ich. "Inventory," vielleicht?