Don't be restricted by the idea that photographic chemicals must be bought from only certain sources. Many like sodium sulfite and sodium carbonate have many other uses that may provide cheaper and more available suppliers. Borax, lye (sodium hydroxide) and sodium carbonate may be found in supermarkets; sodium sulfite from food service suppliers, sodium bromide from pool supply companies, potassium permanganate from water softener suppliers, etc. Do a web search for uses of a certain chemicals for ideas.