My father-in-law picked up a big air compressor for next to nothing. It had a large air tank and lots of hoses and accessories. The only problem was it didn't work. This compressor, like generators, pumps, and many other tools, was built in China. Replacement parts are almost never available.
Just read reviews of Chinese built generators sometime. Ignore the reviews from people who just got one and it fired up. Look at the reviews from people who actually use them for a living and work them hard. Those reviews are terrible. Quite a few are broken right out of the box.
Sometimes it's possible to do what my father-in-law did and fabricate parts yourself. That's what it takes.
I used to look down on equipment that use small Briggs and Stratton engines. They are pretty low tech and have been around forever. Now I look for them just for those reasons. Parts and manuals are readily available.
Good quality equipment is still available, but they aren't cheap. If your business depends on your equipment working, spend the money. That also goes for people who buy equipment for emergency use. If the grid goes down and your cheap Chinese generator fails when you really need it, will you be thinking about what a bargain it was?
There are times when I will buy cheap power tools. If I'm doing a job that needs special equipment, but I never expect to use it again, I might go the cheap route. If the equipment fails it will still be on warranty. I once blew through a pile of guaranteed wrenches. They'd snap and I'd go down to the store, get a replacement and snap that one too. Eventually one lasted long enough to do the job. The store was getting really really sick of seeing me, but that wasn't my problem.
As for my father-in-law's compressor? His cobbled together repair lasted a year. Then he tore it down and did another cheapo repair. He's still using it.