Pressure Washer

How many side jobs do you plan to do? I have a 3000psi/4gpm industrial-grade machine, I don't use it very often but I'll never wear it out either. Most residential units are not designed to do side hustles, get broken easily and have pumps and engines rated to be used only so many hours per year. You might want a more powerful machine simply because it will offer greater durability, most of the better ones have adjustable pressure regulators so you can dial down the pressure. I also think bringing out a more professional-grade machine would look better in the eyes of any customers too. I had a guy ask if I wanted my driveway and sidewalked powerwashed and he had what looked like a curb-picked Troybilt in the back of his truck.

This is the brand you want for commercial jobs.

Mi-T-M

Check out a Tractor Supply if one is near enough, can get a decent Simpson in the $500 - $600 range. You'll probably want to save some money for accessories, extra hoses, spray tips, good supply hoses (never use a customer's, good way to send trash into your pump), and a inlet mesh filter canister to proect the pump. Think most Simpsons in that price range use AAA pumps, usually pretty solid but I've had two develop oil leaks and you definitely want to check the oil level frequently before and during use. Keep extra pump oil handy, AR synthetic pump oil is excellent stuff.

You’re going to have to spend more than $1000 to get the equipment you need to do side jobs.
The machine is about $1200 and you’ll
need a surface cleaner with hand grip handles, that’s going to run in the $600- 800 range.
The one that just goes on the end of a traditional wand will kill your back.
Trust me on this!
As stated previously, Mi-T-M makes great machines and also have reliable accessories, so does BE. Also look at Hydro Quip, but they are very proud of their stuff.

GPM trumps PSI, bought a 4gpm northstar from Northern, cat pump/11 hp honda 20 years ago for doing everything from machinery/vehicles to cleaning A/C condenser coils with the unloader cranked down. Recently bought a WEN 3000#/2gpm washer, it's fine for cleaning my mowers and tractor, but would hate to do houses or sidewalks or even a vehicle with it.