Find a supplier whose products come in concentrated form, that way you're not paying for 10 gallons of prducts and 45 gallons of water.
Also, when you mix concentrates, be very careful about the quality of the water you use. hard water and a high TDS count can certainly hinder a products performance. Part of the beneit of buying your solutions from reputable companies goes a long way to ensure quality products and consistent performance. Also, if something (either a new product or one you've been using) does not work well or as well, you're complaint won't fall of deaf ears.
Blending chemicals is more involved than just knowing a formula, buying the raw materials and getting a mixing paddle.
That said, if you're looking to cut costs on lubricating
soap for your cloth, foam for a foam arch, or brush prep solution, I highly recommend you try a product called Witconate 90 Flake. It comes in 50# bags. One bag makes two 55 gallon drums of brush prep concentrate, 1-55 gallon drum of foam
soap/polish (add dye to color). Cost is about $100 per bag. Its easy to mix and foams like crazy.