If you can't find propylene glycol at a farm store (it is used for cows/sheep) then try your local veterinarians. I called a vets office yesterday and she asked if I wanted it for sheep I told her I just wanted it for a fog machine. She asked how much I wanted, I said 16 oz or less. She had it waiting for me when I got there. I got 20 oz or more for about $10. It is 100% propylene glycol, no additives, U.S.P. (I think that's food grade right?). Obviously if they take it from an open bottle make sure that they didn't add anything to it (they shouldn't, but just in case). Other than that, I use the glycerine from walmart in the skin care section, I know it is only 95% pure but it hasn't hurt me yet. I do not however advocate using it, it's best to use the stuff from the cake isle (wilton's?) but our walmart didn't have it. So, if you use the skin care glycerine, do so at your own risk.