The component cost to build the iPhone 6s is $11.20 higher than the iPhone 6 which came in at $222.80.
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.
Of course, the estimates here do not include certain costs for research and development, manufacturing, distribution, etc.
We'll let you know if come across a more detailed breakdown. You can follow iClarified on Twitter, Facebook, Google+, or RSS for updates.