I question why you need one?
PW is good for businesses that do a lot of neglected cars, trucks that are full of dirt/mud, etc. You dont really need one for washing your maintainted car in your driveway. I would save the ~$150 and spend it on more quality supplies. a foam gun and mitt are going to be more than enough to handle your own car or two.
Plus, add in the time it takes to setup the pressure washer, break it down, etc...I just dont see it being a time saver for the average DIY car washer doing his own car...