I have one like the Harbor Freight one, and it has been so long ago, memory has failed me but I think I got it at an Auto Parts Store.
We have the same style at the shop the guys have been using for several years, plus being thrown around when using. Usually pull the hose to retract and the guage gets a good smack on the floor. Take them up to Auto Zone once a year and they have a air guage test board. I have disagreed by 2# on all of the gauges and they are still just 2#'s off.