According to a new report, the OnePlus 7 Pro only costs US$324 to build. That figure is non-inclusive of R&D, logistics, and marketing costs, of course. The Samsung Galaxy S10+ costs US$420 to build, and here we compare the cost of components on the two devices.
https://www.notebookcheck.net/The-OnePlus-7-Pro-only-costs-324-to-build-Comparison-with-the-Galaxy-S10.427693.0.html