Biotin is a natural substance found in food but it is also sold in the form of a supplement. Health food stores and some supermarkets sell it. I go to a store called Wild Oats to get mine. It depends on the brand and number of tablets in a bottle as to the price. I've seen it range about five to nine dollars a bottle. The best food sources are egg yolks and liver, but those are also high in cholesterol. Only 150 to 300 mcg is required to avoid deficiency. Biotin is part of the B-vitamin complex so it might also be in some multivitamins. It should say on the lable. Hope it works for you!