I was looking at that one too.
Here's my justification to myself for it. I had a trip I went on last fall (my dad's elk hunt in the San Juans) that I spent about $40-45 at the car wash trying to clean up. I got the Jeep about 85-90% cleaned up. (thing was a total muddy mess---I HATE mud). I then was going to spend about $25 spraying off the EJS from two Jeeps. I figured I'd rather spend the $ on something tangible that might have other uses than give it to the car wash owners.
So far, I've washed our fleet of rigs a couple of times, my boy has cleaned the HELL out of my flatbed trailer and my house's rear deck (the sprayer just took some mold type stuff right off the concrete) and will be washing the driveway tonight for a mothers day present in chalk from my daughter to my wife (this'll be awesome, I'm sure). So in coin op carwashes alone, I figure I've saved $50 already. I still have a bit to go to break even on the washer but I do like having it.
I was able to clean up the remnants of the San Juan trip when I sprayed off the EJS this year. (I HATE mud) Then I went out to Wendover for the Salt Flats 100 deal and got my JKU all muddy again. (I HATE mud) and will be cleaning all that junk off tonight while I have the washer out.
That brings me to my "beef" with the washer. It's not really horrible to get out and get hooked up, but it's not quite as convenient (at least in my mind) to get it out vs. running to the coin op. If you look at it from a time perspective, it's probably a coin flip of getting out the washer vs. running down to the coin-op. However, I don't worry about grabbing quarters and about timers when I'm washing. Seems to make it kind of worth it?