I will be getting a 4.5 HP / 21gal vertical one with these spec's $159.99 Harbor Freight, gotta love them!
125 PSI max; 4.4 CFM @ 90 PSI; 11.1 CFM @ 40 PSI
A lot overkill for PC but I am also using it for automotive work so I need the power. I would rather spend the Extra $ and get one that fits my worst case and use a regulator for when I powder coat.