Apple will pay about $234 for the parts used in every iPhone 6S, according to estimates from Bank of America Merrill Lynch.
The biggest part of that cost is $127 for semiconductor pieces, including $36 for the various cellular radios, $25 for the new 64-bit A9 processor, $22 for various sensors (fingerprint, NFC, and so on), and $20 for 64GB of flash memory. Other core components like the screen, camera, and battery will add up to $73, and the other stuff (like the case) will add another $33. The older models are cheaper for Apple to make, as the cost of their components has come down over time.
An unlocked 64GB iPhone 6S has a starting retail price of $749, but that doesn’t mean Apple is making gross profits of $515 in profit on each phone — there are also manufacturing and distribution costs.