I have the four stage CapSprayer and an Accuspray with a two gallon paint pot. I love the Capspary and use it for everything from latex to laquer.
You can pick up a used four stage for around four hundred. That SHOULD be with the hose and gun. I see scammers selling beat units without hose or gun, which would add about four hundred.
The Accuspray has an even nicer gun than my Capspayer, but it is, essentially, a self contained conversion unit. I’ll probably sell it, since I don’t do commercial work anymore.
These are units that, if you follow the rules, will last you a life time and allow you to paint a cabinet in latex or a car in lacquer.
Obviously, the two gallon unit is more complicated to clean. The Capspray, not so much.
Stay away from the Wagner buzz units. No one owns an old [working] one, unless it’s still in an unopened box.