Still cheap? wow... usually the prices begin to get inflated once something is banned.
They do, and in all honesty even in this case they did. You'll really only notice if you have some concept of the originary price. In these case the originary prices are very low relative to the income of an average Englishman, or American. Prices are driven up by the artificial scarcity. If ever there is a period when the artificial scarcity can be overcome (e.g. paying off the prohibitionists to get the product in, finding a hole in the security checks, an increase in particular productivity behind the wall of restriction, etc.) prices will lower as a result of that cost barrier being removed. Competition further decreases the prices.
The same thing can be seen here in regards to the prohibited drugs. Prices fluctuate with the availability of product (high supply in this case), and in spite of the hundreds of billions of dollars wasted on the irrational, evil, freedom destroying War on
some Drugs (in reality a war on people), prices of the most popular drugs (e.g. cannabis, cocaine, heroine, LSD) have fallen decade-over-decade when adjusted for inflation. This only further highlights the absolute abject failure of the War on
some Drugs, that supply is even higher today than it was when the "war" was first started. And you know the government approach to failure: Throw more (stolen) money at it! Throw more men at it! Throw more powerful weapons and tactics at it! In contrast to a business on the market which would simply fold up shop.
In the US, as in all other places, high prices are a signal to producers that there is a profit to be made, and so induces them to increase the supply of the product. This is why the supply is high here. With high supply comes lower prices. So from the beginning: The government is the cause of the high drug prices, as their efforts at prohibition are only to be considered as an added cost of business; The high prices attract suppliers; The high supply brings prices back down. At the root: government. Now tell that to the "drug czar"
Also when it comes to guns, here in the US all kinds of extra costs are tacked on to what should essentially be quite affordable. In the form of taxes, restrictions, licenses, notifications, authorizations, and defensive pricing (lawsuits and all that). In a free market I can't imagine an AR-15 costing more than about $50.
