WOW, I guess you need to evaluate if you're using a homeowner's type unit for commercial purposes. That ain't gonna work.
I bought a Karcher from BJ's a few years. I probably use it every other month on average and have had excellent use from it...no complaints whatsoever. In fact, I've found all sorts of tasks that it can be used for.
I'd never be in a position to need a commerical type unit - - I simply would never put it to use. I've gotten every penny's worth from my $185 Karcher expenditure and it rocks on car related chores. Period.
Home Depot etc. offers Honda engines mounted up to XYZ company pressure washers. My father has one and frankly I cannot understand why he spent the $$$ on it. I think he's used it once...total over-kill.