I must ask what exactly you think goes through the minds of these child pornographers? Are you implying that without this so called "market" that they would be otherwise productive members of society? Safe, normal people don't rape children for the money.
And let's get back to the subject of the so called money. How does that black market economy in illegal information work? Information (including naked pictures of kids) isn't like a bag of crack. It's not a physical object, and can be replicated infinitely from a single artifact. A person so inclined could make available every piece of information he/she had at no charge, underwriting the entire illegal "economy". Image trading sites could decimate any sort of pay site on earth, and smart buyers with similar interests could pool resources, pay only once, and supply the material to hundreds of like minded contributors.
Now, what does that tell you about this business model? It tells me that it doesn't work.
That ignores the issue of trust, which I think is a significant one. Any financial transaction must take place amid an environment of trust. I pay you five dollars, and you provide me a burger and fries. If you don't I can inform the police about this incident and they will retrieve my money. What does a person do when they deal with a child pornographer? Do they also go to the police and say "I sent this guy a hundred bucks and he never sent me any child porn"? Or is the customer to trust in the reputations of these fine, upstanding citizens to keep their words?
Now, with the practical matters out of the way, I'd like to spent a bit discussing the moral matter a bit further. Explain something to me. What difference will the viewing of child porn make to the child depicted therein? Let us assume (as per the business model I've discussed above) that no backing is given to the criminals who created it. What difference will it make to the child? Will the destroying of all the evidence cause the child to be unraped? And how are they to know when the last photo is destroyed? Answer is they won't. From an objective prospective, there will be no difference to the child one way or the other. Either way they've been through a traumatic event (and for the sake of argument I'm assuming that we're discussing a rape rather than a fully consensual act which was simply unrecognized as such by the law), and either way they'll have to deal with that and the fact that it's possible their image is "out there".
It seems to me that there is only one organization which is capable of making a profit in this enterprise. That would be law enforcement. No one questions why the FBI has the most massive database of child pornography on earth. Everyone's so happy when they run their website "stings" no one even questions what they gave away to entice people into ordering their "premium services". What they agreed to do. What they actually delivered in order to "maintain their cover a little bit longer". And who's really keeping track of the money paid to the FBI in the course of these so called stings?
I think there might be a reason why the government is having such a hard time shutting down these kiddie porn rings, and I think it has a great deal to do with the fact that the majority of their customers are within the jurisdiction of the FBI.
A helpful link: