You'll get no better than a solid air cooler heatsink.http://www.tomshardware.com/forum/256607-29-watercooling-read-first
It's unfortunate, but for lower temps (my i7 loads at 55C) it costs a lot more. It's mainly physics.
You need lots of surface area to remove the water temps to the air. Meaning a radiator, they are MUCH more complicated than a Air cooled heatsink. Then you need a really well engineered CPU block to remove the heat. And a quality pump able to move the water at a minimum flow rate and not quit in the 3rd year of watercooling. Plus quality hose etc.
It really adds up fast for a proper quality watercooling loop. I'd like to say $250 minimum but with experiance and some ugly parts you can do it hopefully for $150.
A really good WC CPU loop that will take your CPU and Mobo to the max will be about $300. And using very quiet, almost silent fans.
There is wannabe watercooling, and then there is real watercooling. You pick.