Like Hu said, if you're gonna make money, then you afford to spend some to buy professional quality software. There are, however, some "in between" solutions, designed for hobbiests or part time business users. There is a hobiest version, and a "Mach 2" version of Dolphin Cad/Cam which are both very reasonably priced for their abilities. Check them out at
www.hobbycadcam.com
Another solution for 3d milling is Visual Mill basic, at around $1000. Hope this helps.