Ok, I want to build my own cnc plasma and router table.
I have a hundred questions, hoping some one can guide me through the process.

#1)
I have seen a complete electronics package for around 2000 it includes
motors connectors drives, power supplies, and a manual controler box for 3 axis.

Could I build one for less?
I'm not an electronics tech but I have a good understanding of general electrical components and computers. I have changed out cards and I have flipped a few dip switches.

Another question is around calibration and gearing. I was looking at using gear rack and pinions as an option for driving the carriages. Is there a desired calculation for ratios that are more desireable for the drives? or are they just aobut infinitely adjustable?
What are the pros and cons of gear and pinion mechanical drives versus acme screws or ball screws?