Of course the source from the cheapest possible places, its a business like any other. I know of a few companies that spot test the raw materials before they sell them, but I would think that because of the expense of chromatography testing it isnt done a lot. You really gotta trust what your putting in your body.
I don't do this for my family, my friends, women, accolades, pride, or ego. I do it for me and no one else, its just part of who I am.