I play a lot of FPS and RTS games and I used to be a huge nay sayer about the "gaming mice". Over priced for not much more ...
Until I got a razer imperator... and now I'm using a razer mamba... its a rather amazing piece of machinery.
Theyre rather expensive... so if youre looking for a good budget mouse, the best one on the market ( IMO ) is the logitech MX518... If you sit around tightly, the price on those drop to about 30-35 bucks.