There's a few points I'm seeing here that just don't make sense.
First of all, there is NO WAY that any of us, working out of our basement, could produce a "cheaper alternative" drug to any drug which a corporation is legally mass-producing on an assembly line. It just isn't possible.
The only way a "cheaper alternative" would come out is if another corporation streamlined the process.
There's capitalism for you, in all her beauty. And in this case, it would be a very good thing. Companies compete with each other, drive down the prices, the lower the prices, the less chance someone's going to turn to crime to get their fix.
Secondly, about the casino reference... That's completely different. Before the casino popped up in your region, someone would have to travel far (Vegas, Atlantic City, whatever) to gamble. As of right now, with drugs being illegal, they have to drive a max of 15 minutes to get just about anything they want. Once they are legal, they'll have to drive a max of about 15 minutes to get just about anything they want.
People just don't understand this. There is a far greater amount of Americans doing drugs now then is generally "accepted." I, for one, have never been asked to take a national survey on the matter, and I personally don't know anyone else who has. But I do know hundreds of people who do some sort of illegal drug with a fair regularity.
I *really* doubt that legalizing all drugs will lead to a TRUE upshot of users. I DO believe that legalizing all drugs will lead to a TRUE assessment of how many people actually do it as of now.
I'm sure some people will try a drug for the first time, sure... But I have serious doubts that they will choose heroin, coke, crack, meth, or one of the harder drugs simply because they can't get in trouble for it. I think they'll shy away from them then for the same reason they do now - because they fear for their lives, as they should.
Of course, if the drugs were legalized, and companies were producing them to some sort of government standard (as with tobacco and alcohol), I'd be willing to bet the government would try to set a standard that would be much less likely to kill someone then the crap you can currently find on the street.
Lazs had a really good point about the whole process of cutting up meth. I've seen that done too (amongst other things), and let me tell you, it's really no suprise so many people are dying from the stuff as it is. You wouldn't believe the crap people put in it. It's not all rock salt.