a decent loop once bought "rads mainly" can be re used as you upgrade the system. just buy new blocks.
So i dont see the argument that people spend to much on them.
Last year some one gave me a large box of water cooling stuff. Three rads, two pumps etc. Everything I needed.
Blocks however were ludicrously priced. For the GPUs I had they were £120 each plus the CPU block. I never bought them because I knew how quickly my GPUs would be out dated (two Titan Black).
The problem for me and the one that's always put me off is the price of the blocks. Not only that but the fact that they only fit that one specific GPU and when it's out dated (about ten months going by recent releases) you need to break down the entire system and spend more money on more blocks.
And as I said, most of the time it's pointless. My Titan Blacks ran perfectly well and well within safe limits on their stock air blower coolers. Had I water cooled them I would not have gained much, because overclocking on them was not about temps it was just about how much they could take.
Even if I gained 20% more performance it would have cost me around £300 just to cool the GPUs (because I would need the joiner for the pair).
I've actually just edited out the rest because with things like this it's incredibly easy to insult some one... So I will just leave it there.
When I stupidly spent £3500 on a rig I made sure I had my priorities straight and spent every last penny on power and performance, rather than what it looked like.