Most gauges are just about impossible to repair.
As long as the thread matches, it's good. I know several people who got their low-pressure gauges at pool stores. You might want to look around a bit more for something with a 0-30 psi range. 0-100 makes it a bit difficult to set your regulator at lower pressures.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk