Our mod krpind is in the business so you might consult him (would be wise to do so!).

Before I knew that I bought the "biggest and bestest" at Menards.  I needed a 50' hose so I went to get it.  They don't carry them and can't get them, but the worker whispered I could go to a specialty place (probably like the business owned by krpind) which did nothing but sell pressure washers.  It was an hour away, but I called and found they had what I wanted, so I went.

First thing I see, immediately inside the door, was a unit with the same features (pressure, gpm) as mine, but with a solid brass manifold (mine was shit pot metal (zinc)), as their "monthly special"--for $10 cheaper than I paid.  I had already used it so I couldn't take it back.

It's been years, but for the last three years it leaks where the hose screws onto the manifold.  No fix, but I can replace the manifold for $150.

I'd talk to a pro and have your needs assessed, then buy a GOOD ONE, as it is a long-term investment with proper maintenance and winter storage (if it freezes where you live, didn't notice).  I paid $389 but a MUCH better unit is around $700.  For light homeowner use the $400 one would be adequate though.  For the extra $ you get a much superior Honda engine, and maybe (don't know) a better pump.

For the few times a month user a cheap one will be fine if you want to save money.

Make sure it is a horizontal shaft engine and not a vertical shaft.

You can step up to a Honda, but the chinese clones are pretty damned reliable nowadays and for the money it is hard to beat since Honda and every other manufacturer is just as liable to have problems as any other engine considering most of the issues we see are due to ethanol anyway.

A triplex pump is preferable, but not needed for a twice a month unit that is going to see limited run time.

Personally I would buy a Honda GX390 mated to a Cat/General/AR/ Comet pump and be done for life with the type of use you are talking about.

What you really want to make sure you have is an unloader that isn't integrated into the pump head but a complete and separate component. (see the pic of the cat pump in this thread of an example of a pump with an integrated unloader) That is typical of a unit that was left running in bypass, without the trigger being pulled, until the heat got so bad that it melted the plastic sight glass.

You spend a bit more and you get a better pump, components including unloader, hose, trigger gun and even nozzles.

I'm laid up at home right now, but I probably have some pics on my phone I could add. Let me check.

That isn't even the pic I wanted to post, but it will do.

That unit, while a belt drive shows the unloader that is a separate component instead of being built in to the pump head. That little black hose is the bypass line that allows the water to go into a loop when you let off the trigger. Look for a unit that has that.

That unit is/was about $1100.