Physical goods are not the same as digital media, or ideas and concepts. Different rules of supply and demand apply to them, because in the abstract world scarcity is only artificially imposed by keeping secrets. The law of karma is far more important here, because you rely on your clients being honorable. If you screw enough people over, someone who has your content will get pissed at you and start offering it for free. And others who might have been willing to pay a reasonable price, will now get it for free.
This is not good, or bad. It is the nature of this economy. Play nice, offer something of value, and listen to your target audience, and you can be profitable. Be greedy and try to control everything and people will laugh at you as they distribute your precious "secret" to everyone who wants it.