This could be both a state and Federal crime. It matters not which federal or state agency would do the investigation; they will not 'announce' themselves, they will just do their work. Likewise, it doesn't matter much which government gets to his first, although the federal sentence guidelines normally provide for a longer term than California law. If charges are filed by either jurisdiction, get an attorney immediately. Perhaps he should have one waiting in the wings, because sooner or later the govt will get him.
Although I am an experienced CA criminal defense and appeals attorney, I can not 'guarantee' that my answer is entirely accurate, since I have not reviewed all of the factual circumstances of the case, nor have I discussed those circumstances fully with the questioner. The fact that I have answered this question does not establish an attorney client relationship between the questioner and my self or my office.
Not very much time in the federal minimums. It is a schedule IV drug, meaning it the least dangerous. Getting busted selling 3,000 pills by itself does not get a minimum. But the feds would likely add a few groups of the 3,000 together to get him up to a minimum. If they can prove he sold more than 4k pills, then the minimums kick in. Starting with a few months up to several years.
The next question would be whether this person is a pharmacist as that may provide some level of protection, but wouldn't make him immune I wouldn't think. The fact that he is using the mail would expose him to additional punishments.
What this person is doing is very stupid and flamboyant. He should stop and find another path to riches. This can't be worth the hassle.
The above information does not establish an attorney client relationship nor is it meant to provide legal advice.