if you have a air compressor and can tolerate the noise a venturi vacuum pump is cost effective to buy new.
yYou could go to the you pull it junkyard and search the cars for booster pump.
some cars mostly european had a small vacuum pump for cruise control.
the cheapest is a piece of hose to suck on with your mouth.
And of course running gasoline engine usually can supply vacuum.
And the hand vacuum pumps.
A distributor machine usually has a adjustable vacuum pump too.