If growing tobacco were made illegal in pretty much the world, but possession and sale of it were still legal, the price of tobacco would skyrocket, way past the even $6 a pack or whatever they cost in the states that tax the hell out of tobacco.
Hell, replace tobacco and use tomatoes or lettuce or whatever you want in that analogy. When you restrict the supply, by whatever means, the price goes up, especially if there is a great demand, and especially if the risk of procuring the supply is high.
Legal and regulated, unlike tomatoes and lettuce. And pot would be regulated. You do that, and you start driving up the price right there.
You'd have licensed growers, licensed manufacturers, licensed sellers, federal inspections at every level, manufacturer's provisions for lawsuits, etc., all adding to the price. Then start adding taxes at every level of government.
"In both instances, supplying it is still ridiculously expensive, as it is illegal to grow it in any sort of quantity that would increase supply and reduce price."
You're reaching.
Sure, increased quantity would reduce costs. But what are we talking about? Reducing the cost from $3 per plant to $1 per plant? On a product selling for $300 per ounce?
"the price of tobacco would skyrocket, way past the even $6 a pack or whatever they cost in the states that tax the hell out of tobacco."
In New York, it's over $8 per pack. Now you tell me why that is so. Tobacco is as cheap to grow as marijuana. When I was younger, I remember paying 35 cents per pack, and I thought that was a lot. There's no reason cigarettes should cost $8 per pack. But they do.
So let's not get all cocky talking about legal marijuana being cheap. I gave you the two best examples of legal marijuana, and the legal selling price isn't even close to the actual cost of producing it. It's actually less illegally, and those dealers have more risks.