Actually, Jev, Salvia divinorum itself is classed as a Schedule I drug in 15 states (I think), making its sale illegal. So far, I haven't found any legislation making it illegal to grow. That said, although it's a relative of yer garden variety sage, it's a really picky plant that, I'm told, is quite difficult to grow. (Haven't tried myself.)
As far as the fake pot, bath salts, etc., sold in head shops (and sometimes at the local convenience store), you're right. It's not the herb (whatever it may be) that's the issue, it's the added chemicals. Here in Georgia, they're having difficulty keeping up - every time they pass a law outlawing some chemical or another in that crap, the manufacturers just put something else in. And despite the plethora of news stories on how harmful it is - even to the point of fatal, kids, in their infinite wisdom think it won't happen to them & try it anyways.
I'll stick to the stuff that comes out of my (or a friend's) garden, thanks very much.