There are DIY places everywhere, the one place I tried it worked out pretty well, they condition the rinse water so you don't get spots and with avoiding the brushes and the high power spray you should be able to give it a nice rinse for only a couple bucks whilst still babying the paint.
Just an example, I have no idea how good it is, some can definitely be worth avoiding:
http://concord-ca.patch.com/listings...-easy-car-wash