Thermaltake ProWater 850i
One of the more complete kits, the Thermaltake ProWater 850i is just one of the incarnations of Thermaltake Liquid Cooling Kits, perfected through several different models. In my humble opinion, this kit includes just about everything a person could want or need in a liquid cooling system.
In addition to the standard and required features of a pump, radiator, reservoir, tubing, and fluid, the kit includes the tube wraps for crimp prevention as well as an optional flow meter to ensure that your system is operating within the optimal parameters.
You get all of these features, plus a warranty, for only $140 retail. To assemble these components individually through a company such as Danger Den, which specializes in liquid cooling components, would cost quite a bit more - possibly hundreds of dollars.