A lot of different polishes, sealants and waxes are compared here, but very little about car wash. I know there must be differences, but are they worth it? I have been using Meg. Gold Class for a couple years. Now that I'm reading forums on detailing and looking at vendor sites, I see that I can pay up to $17.95 for 16 oz of Pinnacle Body Works Shampoo, and there may be some more expensive. Is the expensive stuff really worth it?