That's because you can't equate the two like that. The more expensive CPU will always give more performance because it inherits more power to begin with.
It's like saying:
A) Buy a Porsche 911 GT2 at ~$200,000
B) Buy a Evo Lancer ~$30,000 and pour ~$100,000 to fix it up.
The Porsche is inherently faster than the Evo, no matter what you do, its top speed will likely never match the 911. On the other hand, you're still getting similar performance on the whole such as acceleration times, braking distances, etc. The same as the CPU, as your CPU likely never at 100% load 24/7.
If you get a very expensive CPU and a cheaper cooler, you'll probably get more performance regardless but you're getting less for your dollar.
If you get a cost effective CPU and a more expensive cooler, you'll get less performance, but you're getting more for the dollar.
The Q6600 can hit really good speeds even on "cheap" cooling solutions, like the Xigmatek mentioned earlier. In all reality, a budget/mainsteam CPU with an air cooler will give you the most out of your money, regardless whether money is a problem or not. Tom's Hardware showed that an E2160 clocked at 3.0GHz can almost keep up with a Q6600 clocked at 3.2GHz, and the E2160 only costs around $70USD, nearly 1/3 of the cost of the Q6600.
The Zalman Reserator costs $420 and you can it for future upgrades right? An air cooler at the 1/10th of the price gives 90%+ of the performance. At $420, you could buy air coolers for the next 5 CPUs and still have cash left over while retaining 90% of the performance and a lot less maintenance.