Homebrew PCBs

Hi,

I hope I'm not re-asking a worn out question... but here goes. What is 
the best tool to use to route printed circuit boards on an NC mill? I 
have a Sherline mill with the NC kit, Xylotex controller, and Master 5 
as the controller software. I am using Eagle PCB for designing boards. 
I just need to know what the best (meaning least expensive but giving 
good results & life). What does LPKF and the other board router 
devices use? Is Grizzly a good source? Tool steel or carbide? 

Thanks!

Bob