overclocking the monitors.. reduces the lifespan.. you can try with the korean branded monitors.. cheaper.. but I'd stay away from OCing as you hardly get any actual benefits (OC to 200hz etc is VERY VERY rare) and it's not guaranteed that the monitor you get can actually be OC'd.. 95% of the times I've seen are that you get maybe 5 to 10 or 15 Hz increase.. not worth spending so much and then making it go kaput by 'OC..
200hz gives you smoother & better visuals than 144Hz.. However, your GPU MUST have the capability to push a 200FPS constant.. (1080p in my case) so you tell me, if you got a GPU that can maintain 200 FPS constantly throughout the game, I'll say, go get it.. else, it's just burning cash.. i know a few of my friends...