Yes, everyone knows that you've got to sell it for more than it cost you. But the cost of manufacturing is irrelevant to the value the customer is willing to pay for the product.When the cost of manufacturing exceeds what the market will support, the company will go bankrupt.
The cost of manufacturing feeds into the price point you want / can sell at... Particularly for labour intensive steps, like QA.. important in this context... And Boeing
I'll point out too that the idea "QA costs more" is only true for poorly defined processes without proper control. Yes, if you try to inspect quality into the product once it's built, it'll cost more. So don't do that. See "Toyota Production System".