hobo fright has a manual tire changer, but after looking at it, i would look elsewhere.
30 some years ago, i got tired of being ripped off at the only shop in town at the time, so i built one.
it wasn't that hard to build. i used to have pictures, but i can't find them now.
the hardest part of the build was to get the right leverage for the bead breaker.
over the years, i have accumulated an assortment of spoons, bars, and bead protectors, as well as protectors for wheel edges.
the biggest problem with used commercial machines, is parts availability if something is broken, as well as the physical footprint needed if space is at a premium.