One other important reason to use precision ballscrews is so that you can do nice accurate circles and arcs. Backlash is a real bearcat to deal with as the machine is crossing the quadrant lines (from X+ to X- and Y+ to Y-). You'll be quite limited as to what you can do with your cnc if you're always battling backlash.
Whats that saying? The bitter taste of low quality remains long after the sweet aroma of low price is long forgotten.
Spend enough money to do it right the first time, or don't spend a cent.
