Supplements can be purchased at your local drug store, health food store and grocery story pharmacy. You can also shop online. Please read the labels carefully as the doses can vary drastically from one company to another.
Compare prices with these online purveyors:
Swanson Health Products: 1(800) 437-4148 http://www.swansonvitamins.com/
VitaCost: 1(800) 381-0759 http://www.vitacost.com/
Professional Supplement Center: 1 (888) 245-5000 https://www.professionalsupplementcenter.com/