Liquid cooling is kind of extraneous. It's a mid-way point of cost for good cooling. Better than air (*I'll explain in a sec) yet worse than phase change or LN². It's expensive to go liquid for even a one block loop. But after you buy your main components, it's cheap to upgrade.
Consider this:
I spent 60 dollars on my block, 160 on my pump/res, and 50 on my rad. Plus 14 dollars times 3 for comp fittings on each unit. Plus 22 dollars for tubing, and 40 for 2 liters of liquid. Assembly isn't terribly hard.
All in all, about 375 dollars for a CPU loop. Oh, and add another ~20 dollars for two scythe 3k's. Ok, so we call it 400 dollars for the whole loop.
***Temperatures that are typically 5-6 lowers than a really good air cooler. and temperatures under load that are WAY better than a really good air cooler. Mind you, this doesn't include TEC's. I have expandability, and temperature stability, and a small risk. If you choose the right parts, there is no risk. none at all.
But it's an expensive avenue to undergo. And it requires maintenance. You have to clean the radiator fairly often to keep it from getting too bad, and you need to drain and refill the system every 8 months or so. Plus initial burping.
All in all, if you have the spare money, do it.