I have gotten organic yellow corn from Amazon and i just ordered some blue and organic white from the Roveyseed.com. They supply the tortillaria in queens, NY and they are very nice people. The idea to use the ultra pride came from this thread! I got a used one for $95 and shipping on Ebay. The friend who is teaching me is from Mexico. Her mom, who still runs her farm in Mexico, was in New York and came to my place for a quesadilla dinner and wanted to know why we would ever use masa harina, when we could make it ourselves. I took it as a challenge. Cece has guided me and says the texture is spot on and our tortillas taste like Mexico.