You can build a better inaudible kit for the price of a Zalman kit. In some cases, the Zalman passive kits perform WORSE than the stock cooler.
Zalman is far more expensive than a customed kit. However, they do provide EXCELLENT temp's for a fanless
WC system. My Reserator keeps my P4 630j @ 42c when running F@H on both cores...and has my 7600gs [vmod'd to 1.41v] in the loop. Overall...I would not say those are bad temps..at all.
In contrast, I spent ~250$ on the Zalman and about 180$ on my DD kit, which I pieced together. Performance is better, with the customed system, but my fans put off around 40db...which is like a motorcycle sitting next to the Zalman.
I dont regret buying the Reserator, it is very reliable and easy to maintain...that alone is worth a little extra $$ in my opinion.