Could this work for a pump

Can you buy like a $15 pump without a gauge, then buy a $20 vacuum pump gauge and put the pump/gauge on the cylinder and detach the original pump thing?

Yes you can. I bought a cheap pump without a gauge and have used it for a short while. I had worried about not knowing the vacuum level so I bought an “actron vacuum pump” with gauge from and auto supply store (it is in the brake section, $29.95). It came with about 24” of rubber hose that connects onto the end of the cylinder nipple.

For your information, the cheap cylinder pump allowed about 4-5 in.Hg. before the relief valve opened.

Halloweenie

How would you go about taking the original handle off and putting the pump with the gauge on to the cylinder?