The law in the US differs from here in the UK. Rick Collins is THE legal expert (google him). The grey areas, legally speaking, are TRT therapy (drugs prescribed legally by a doctor). You could also, if you lived near enough, go over the Mexican border, get some steroids, jab it in and come back over the border and there is NOTHING the US authorities can do.
However (as here), sending drugs in the mail is illegal. You can (and people do) get a 'strike' for every UNIT of the drug. So 100 dbol is 100 strikes. That's just for possession and self use. Sale and distribution takes the offenses up a notch. Even selling some to a buddy is included.
All that said it's kinda stupid. The so-called war on drugs has failed. There are a TON of drugs which cause a million times more issues for the federal authorities that roids do. People take ONE Ecstasy tablet and died. One jab of H and died. Steroids... no, no, no.