I am a beginner but this is what i would have in mind:
First thing I would do is find a nice shop or garage, the bigger the better! The less the price to buy or rent the better! I would make sure it has proper electrical outlets, and good lighting as well as location.
I would look into finding stuff that works for you, and buying by the gallon, or 5 gallon if you get really busy and need it. (Meguiar's Detailer Line)
I would pick up a Rotary, Cyclo, and PC. I would also think a pressure washer would be very help full, along with a nice Big Shop Vac, and a carpet steamer and extractor. Don't forget lighting, you want the shop to very bright! (Home Depot) A Washer and Dryer would be a plus.
As far as products, you want to be able to tackle everything. You may want to find a good APC for engine decreasing wheels and vinyl cleaning. Polishes that will take care of defects as wells as different degrees of swirls and scratches. You will also want to a few sealants & waxes. Wash mitts towels and accessories by the dozens.
Some Manufactures products that I like and you would probably find around the shop would be. Meguiar's, Auto Magic, Poorboy's, OXO, Gliptone, etc.
This is if I had money, Right now I only have a PC, Shop Vac, Presure washer, and mostly meguiar's stuff, and PB's stuff. I think with what I have now I could get by fine with, I would just order gallons instead of quarts. If I could get 1-2 cars a day, and a helper I would be so very happy, and oh if i new how to use a rotary! :hah