Nothing new to add other than backup what’s already been said.
I used a cheap eBay special for many many years. I a used small lead acid battery with a lead so I didn’t have to plug it into the car. Screwed everything to a panel and then attached a Jerry can you that so it was an all one job although looked terrible and the electronics where open to get splashed. But nothing bad ever happened to me in many years of use.
I now have a Worx One and it’s more powerful and convenient to use as it’s in more compact and better packaged.
If money is tight go for the cheap option it worked very well for me for many years. If you can justify the cost of the worx then it will be a much more convenient solution.
I found I could wash two heavily muddy bikes with sticky clay mud with only 10l of water.
Trick is to use a brush to shift the mud. If you try and blast it with just water you’ll use up lots.
But if you do a quick splash to soften the mud. Attack with brush and cleaner and then finish with a good rinse the water will go a long way.