I used to professionally detail cars for a living. Mothers is easily among the best wax and cleaning products. If you want professional quality products go with what you local new car dealership. You can normally buy bulk supplies from them like 5 gallon jugs of soap, etc for cheap. Even better then buying from the dealership, ask them about their supplier. Alot of dealerships get their supplies delivered from a mobile dealer who comes to them. If you buy through the dealer you can normally get items at cost plus tax.
For soap, cherry bomb is the best ive used and i wont turn to another. For interior plastics and carpets, there isn't anything better then xtra duty. I've gotten nearly impossible stains out with this product and you can use it in nearly any surface. For tougher stains and such, eradicator is the best, just don't use it on black plastic. Any other questions just ask.