Price limit?
A crappy (read: just as good as normal air, but with water in its name) water cooling setup will set you back about $100.
Gigabyte's system is good for its $150 price tag and then after that you start going into Swifttech and Waterchill area which go from $200 up to $450.
This is about the best budget system for water cooling you're going to find:
http://www.frozencpu.com/ex-wat-92.html
Now, I dont think water cooling is ever nessacary for a stock clocked system. I think tradiontal air cooling (check Zalman's 9500 for a godo queit but great performaning solution) is plenty unless you really want to OC.