Well you usually do it for higher-end components, so the price of the GPU or the CPU you are normally going to water cool can easily be much higher than that. Furthermore if you want to add lets say the CPU to be water cooled as well the cost does not increase very much as there is no need to double the component need.
Roughly 250-300 EURO in Europe for the water cooling components only.
The GTX 1080 video card and the rest of the hardware is not included... :)
Quite expensive I must say, but I'm sure it is worth it! :)
Well you usually do it for higher-end components, so the price of the GPU or the CPU you are normally going to water cool can easily be much higher than that. Furthermore if you want to add lets say the CPU to be water cooled as well the cost does not increase very much as there is no need to double the component need.