Depends on your needs really.. I've got an electric Karcher that I've had for at least 12 years or more.. It's only 1200 psi I think? But, does everything I need it to do including my driveway and walkways, siding on the house, whatever... :)
I'm sure a 2500+ psi gas powered unit would be a lot faster/better or whatever, but for what I use it for, it would be way overkill..
For a paint sprayer, I have one of those electric hand held jobs and it's over 17 years old and works fine too.. :) I only use it maybe once every couple of years, but it works every time I need it! :)
Good luck!
Mitch