I got a Troy Bilt 2700 PSI Honda GCV160 off of Craigslist for $50 that wouldn't start and the pump was in rough shape.
$120 later and it works great.
Brigs and Stratton was the maker... They are for a bunch of these machines and the others just throw their labels on them. Troy Bilt doesn't do warranty work nor do they have manuals on their website for this one.
There are only so many pump builders and engine builders. Most can be interchanged with an extra hole drilled in the platform.
Horizontal vs vertical shafts - Horizontal shafts seem to have beefier pumps and cost more.
It's really easy to take the pump off of one. I'd recommend taking it off and storing it inside\somewhere it doesn't freeze during winter as the most common thing that destroys the pump is water freezing.
You will need to rebuild the pump as part of normal maintenance.
Starting the pump with water flowing though the wand helps it not take a hit\helps last longer.