if you buy a retail processor, you get a perfectly adequate heatsink.
the stock one is designed with 24/7 operation in mind, not that it is the best one available, but you don't need better for normal usage. people get carried away with heatsinks...
Independant thought is good.
It won't hurt for long.
The best one for the money is the Volcano II for $8. The next best value is the FOP32-1 for $14. There are a lot of heatsinks that cost over twice as much that DO NOT cool better! Only a few of the "high end" heatsinks are actually much better, and those are for the extreme overclockers or cooling freaks.
In my opinion, the fan used on these Heatsinks is the major factor in cooling. Cheap fan, cheap cooling. A decent quiet fan will do wonders to a stock heatsink. A little lapping, and some black spray paint for the fins. Tada, a $40 cooler for $10.