I'm sure I am completely wrong, but...
I'm of the mind that most of the good products you buy are actually good. If you have 2-3 boutique or pro products to do a particular job--like dash protection, carpet spots, tires, windows, paint cleaning (of a single level)--you have more than enough.
For eg, I have about 10 bottles of window cleaner of various kinds. I tested them all, and have a preference (Stoner's IG). For non-tinted glass I use a cheaper local distributer version that smell's better, and the can is lighter and easier to hold. Zep 40 works fine, but I find it heavy. Gunk is the only brand I don't prefer, mostly because it explodes all over the car.
But even then, I would be fine with only a couple of brands. Now I'm using them up here and there, on the windows at home and my shop.
I have three good dressings: 1) Zep All Around, which I hate, but sometimes people want an awful looking shiny dash. I also use it for wheel wells. 2) PB's NL & 3) A local product which just a little more shine than NL. I've been impressed with the Teflon for black interiors because it lasts months, but I'm good. If it goes on sale, I'll try it.
And the list goes on.
Yeah, you can stock up on waxes. It's the cool thing to do. But remember that you can do 20-40 cars/applications which the average bottle or can of wax/sealant. I have 10-12 bottles, though 3-4 of them are half gone. At a minimum, then, I have enough wax for 200 cars. 3 of them are inferior, and I use in certain situations, but I still am over stocked.
The thing is, you get to the point where you'd rather not be using anything but what you really like. There are 3 or 4 wax brands I would try a sample of, or trade with someone or buy on a big sale. Other than that, I'm looking for innovation only.
Rather than spending a lot of money on products you'll never be able to use (unless you are Rabbi on coat # 341), spend your time honing your skills. I think detailing--except protection time--is 90% skill/10% amazing products. There are a few exceptions--the dealership I own has a product that is unbelievable on paint work and can be used by a trained monkey. But I think it is the exception that proves the rule.
