Where to buy tempeh setting powder?

Hello all! I really want to try my hand at making homemade tempeh, but am having an unbelievably difficult time locating the elusive tempeh setting powder. I've checked whole foods, sprouts, sunflower market, and vitamin cottage to no avail. Also, none of my internet searches for local stores that might sell the spores yielded any results either. I live in Denver, Colorado. Any ideas of other places I can check before I have to break down and order the setting powder online?