Mcmaster is so expensive. I use these guys
http://www.dudadiesel.com/viton.php

I also disagree that you can use rubber hose with biodiesel. You may at first experience no problems with regular rubber. Thicker rubber will last longer. That's the way corrosion works. It will slowly eat away at the wall and eventually burst the hose when complete failure has occurred. It could take some time. Lots of research has shown that biodiesel is corrosive to rubber and not recommended for use with regular hose. Viton can be overkill, as there are other types that can handle it, but it is the best for it in overall resistance. There are also many other grades too. Not all viton is the same and not all viton handle the same corrosive fluids. Most of that expensive hose you're finding is still the cheap grade A. (Grade A is all you need for biodiesel)