Cost of a PC monitor = the cost of a TV to use with a console. Do you count the cost of the £500 TV in your lounge when you count the cost of your PS4? In my case, I've had the same two monitors (dual screen) hooked up to my PC for around than 10 years now- and one of them was free second hand in the first place. My lounge TV, on the other hand, I chose specifically and spent good money on not so long ago.
Cost of a router applies equally to both console and PC. Both of them need to connect to the internet, and both of them will have the same "advantage" in reduced latencies, if you're so inclined.
So the cost of my PC which could be fairly compared to a console would be- the PC itself and all internals came to around £500. The mouse was £50, but it is getting towards 10 years old now (was a good Logitech MX518, and is still going strong). The headphones were about £7.50. I own a joystick, and although I hardly use it I'll include the cost- it was around £25, bought in an offer along with X-Wing Alliance back in 2000 or so (Microsoft Sidewinder, still works perfectly). Keyboard came bundled free with the PC case (as did a decent mouse which I don't use). So total cost- perhaps £580 or so, ignoring the fact that several peripherals have survived multiple PCs.
More expensive than a console with a single controller, sure. But not exactly breaking the flipping bank.