I can't speak to a different combination being less expensive, or better function, etc. However, I have been using the CamBam/Mach3 pair for about 3 years now and am very happy with the functionality, reliability and ease of use.
CamBam is a small player in the CAD/CAM world, however, it meets my needs. What I really like is the support people receive from the CamBam forum either by the CamBam author or by user/experts that are very active on the forum. There have been mulitple releases over the past three years with each adding functionality.
I have found Mach3 easy to use, reliable and flexible enough to manage 2 different configurations I use often. I am only using a fraction of Mach3 capabilities so am not wanting 'more' from Mach3.