I'll admit that I don't know a thing about the supplement business, but I can do a search. No one else has responded with anything useful so I'll just refer you to the following prior work. Best wishes.
Progress Thread - Eskil's Progress Thread: Starting a Supplement Business from Scratch
Recommendations? Private Label Supplements?
Supplements Business? YES OR NO?
Supplement Entrepreneurs: Exercise Caution
Progress Thread - Axiom's Supplement Company
Digital/Web - Creating your own fitness supplement or beauty products
Progress Thread - Eskil's Progress Thread: Starting a Supplement Business from Scratch
Recommendations? Private Label Supplements?
Supplements Business? YES OR NO?
Supplement Entrepreneurs: Exercise Caution
Progress Thread - Axiom's Supplement Company
Digital/Web - Creating your own fitness supplement or beauty products