$100 for a water kit would mean that kit is shit sorry to say. Most cheaper water cooling kits get there ass handed to them by a high end heatsink and a good hsf. The only real advantage of a watercooling setup (if your not an overclocker) that I can see is that it would create a lot less noise and still do a good job.
There is a very good review of a watercooling solution here
http://www6.tomshardware.com/cpu/20030616/index.html
I agree with Soggy, in the case of watercooling, you should always look for a good one no matter the price. Expect to pay a lot for a good one too. The kit I priced up here in Canada would run me around $550 CDN soo around $300 US. Now that was a full setup with HDD coolers, and a good Vid Card cooler.