1) At your budget, you are looking at a $200 cpu. Today, it is hard to beat the 2500K.
2) With modern air coolers, there is no real advantage to liquid cooling. Liquid is more expensive, noisier, less reliable, and does not cool any better than a $30 air cooler in a well ventilated space. For a first time builder, it is even less recommended. The only rationale is for bragging to the uninformed. Those who know better will snicker. Put the savings to better use elsewhere.
3) More importantly, what do you want the pc to do? Gaming? Or, heavy multithreaded app processing? or???