I spent big money on the Dupray Hill Injection steam cleaner and really haven't put it to much use. It cleans interior surfaces really good, but it's not a huge time saving over just using an all purpose cleaner and towels. Its good for some spot cleaning, but I also have a small hand held one (forgot the name but is the yellow and gray one sold by autogeek) and that one was about 1/20th of the price I paid for the Dupray and spot cleans just as effectively. My 2000 Watt generator can't handle the 1600 running watts of the Dupray cleaner either.
I would recommend the handheld one from here just for spot cleaning. Its much smaller and slightly cheaper than that one you are looking at.