No business wants to share it's internal costs, it's their prime competitive advantage
Now, the federal government, particularly with drugs pricing, turns a blind eye towards the suppliers just jacking up the purported cost. E.g. Pharma:“we want to make $100 per pill, it costs us $5 to produce”. Fed: “we demand cost + 10%, because the people”. Pharma:”Fine, let’s say it costs $90 to produce.” Fed:”Where do I sign?”
Whereas Walmart would say to somebody like Nabisco, “GFY; if you want your product on our shelves, you’ll open your books and give us audited cost + 10%”.
If your business' primary competitive advantage is that it gets ICs for 1c less/per thousand, your business is built on shaky foundations. One that you would still want to disclose during negotiations ("yeah, our product is the exact same quality as Widget Co; but we've found a supply for some internal parts at slightly below market value").