I feel that if your medical opinion brings you to recommend a particular supplement or substance; and that item is not otherwise readily available locally; and, you can look at yourself in the mirror and honestly say that you are not coercing a patient to buy from you or bending reality to recommend that item; then making it available is providing a service. I think what you charge is not an issue. I would think of this as a variation of the definition of "Fair Market Value":
1. Prospective buyers and sellers are reasonably knowledgeable about the asset; they are behaving in their own best interests and are free of undue pressure to trade.
2. A reasonable time period is given for the transaction to be completed.
