Here is a cluster of gears that I cut on the Haas Vertical CNC 4-axis at Michigan Tech when I was affilited with Team 857, Superior Roboworks.
It can be done...in fact We built two robots that season, so we made twice as many gears as pictured there. I also made a 16" diameter, 12DP gear which anchored our turret.
We saved tons of cash. The involute cutters we bought were cheap. We used regular old 1018 steel, but later manufactured the final stage out of AR400. Still quite a bit cheaper than off-the-shelf components, plus you can make them any size or style you like.
We cut blanks for these gears on our waterjet.....when it came time to cut, we did them all in one shot, 4-6 gears at a time.