Lets take the Xbox One for example...
£430 - console
£20 - Recharge kit
£40 x 6 = 240 - Subscription cost for the likely life of the console to be able to have basic function and online play
£45 - Extra controller
£45 per game
So I'd say with the purchase of the Xbox One you will be spending a good £600, which I will say if you have an existing PC is the price you can turn your current PC into a high end rig. Use the case, dvd drive, maybe the ram, HDD and some other things. Really you could buy a Mobo, CPU and GPU and spend a good £600 on that. You wont need to buy anything else as you can cannibalize what you have, nothing is proprietary like needing a new keyboard and mouse to fit. I personally spent £100 on the mobo, £150 on the CPU and £200 on my GPU, that's basically the cost of an Xbox One. I just used my existing parts... if you need to buy new stuff then £150 can go a long way to getting a cheap case, ram, hdd...
Then you have the advantages of the PC, the mods, the Steam sales, the fact you can buy game CD Keys when they come out for £22 on brand new games. You can also wait a couple months and you know loads of these brand new games will be like 75% off on Steam. F2P is so rampant on the PC, you don't even need to spend a penny on the PC if you do not want to. You don't get that experience on the consoles, you must purchase everything at crazy high prices because it takes so long for console game prices to go down.
If a part on your PC breaks after the warranty, it is so cheap to fix it, if games aren't looking as great as they used to be like an ageing console, it is so cheap to make a single upgrade. I've had my old CPU/Mobo since 2006/7 it was a q6600 or something, a quad core and it lasted 7 years and it still didn't really have any issues, I just felt like it was time to upgrade. My last GPU was from 2009 and it was cheap, this GPU I got is cheap too, if you buy stuff over time and buy smartly, it ends up being very cheap. However once the Xbox One is out of warranty, if something goes wrong with it then it's a new console or a crazy price for a fix from Microsoft.
You have to think as well all the services you get for free on the PC, yet the Xbox One will not have most of them, the ones it does have are behind the Gold subscription! It's a total rip off that you need to pay to be able to use stuff that is free anywhere. The GameDVR is crap, you'll still need a capture card if you're serious about recording game footage, a good one of those will set you back hundreds, yet on PC all you need is Nvidia Shadowplay or whatever which is free software.
I can spend very little on the PC, games are cheap, I can upgrade for cheap and my games will look way better than on consoles and at a higher frame rate. My Library never dies, it is always there, where as on consoles once the console is dead, you have to use an ageing unreliable machine to play them and your games don't move on with it.
I bought 3 games and it come to £135.......... like no wonder why most consoler owners only buy a couple games a year. I've bought 10 times that for the same amount of money on the PC, I got Bioshock Infinite for £6.25..... I've paid nothing for DOTA 2 and played hundreds of hours...
Don't let consoles fool you, they're way more expensive than the PC and as we see already, these new consoles are still struggling to hit 1080P and struggle to use AA already.