Looking for best source for nystatin powder or capsules

Hi, I'm so happy to find you guys! I was recently diagnosed with mild to moderate dysbiosis with both an overgrowth of bacteria and candida (based on the Organic Acid Test from Great Plains lab). I was diagnosed with celiac (through biopsy) in November 2010, and have been on a gluten and lactose free diet since then. I am currently in the Challenge phase of an Elimination Diet that I started in early December, which included no yeast products. My doctor wants me to get the nystatin capsules from the compound pharmacy, but it is very expensive. I realize the generic is probably not ok, but I am wondering if there is a brand name of nystatin that any of you recommend, either in powder or (preferably) capsule/tablet form. My prescription is for 500,000 units (1-4x daily - with gradual titration). Thanks so much for any advice!!!