Your clueless Masayasu Ito the executive VP of SIE said this in regards to skipping on a UDH player for the PS4P "It's a balancing act, you have to look at the cost and a 4K Blu-ray disc player would be costly," So clearly its a considerable expense and its coming from a authority in the know. Again they are using the same exact main components pushing the system and the price difference is minimal, because they are buying these parts in mass quantities where they are already getting the best possible price.
This is a FACT. Again :
Sony aimed for 399, MS aimed for 499. That's a fact and 100$ and year later release are big difference and it can allow to put a more components with higher clocks, FLOPS etc. and some components become cheaper through time, even in a few months.