It depends on a few things.
Does your case have room for a liquid cooling setup?
If not are you OK with having the coolant tank outside the case?
If you decide you need a new case look for one that has Knockouts to run the tubes to the radiator through.
You should be able to set up a watercooling system foe well under $450. It would probably be easier to get a kit than buying individual parts
.
Here is what newegg has in stock today (2 pages). Browse through them and read some reviews or download some manuals and you should have a pretty good idea of what it will involve.