Don't buy kits....research your parts and don't half *** it. A cheap watercooling kit compared to an expensive air cooling setup is:
more expensive
not any better performance wise
a pain in the arse
buying a cheap kit is like buying a dell. Research your parts, plan everything out before you buy (i.e. where the parts are gonna go), and you'll be happy you went with water. If you do everything on the spur of the moment and go cheapo, you'll be dissapointed. If your not ready to pay for good parts stick with air until you can afford em.