Why not criminalise only selling? If you criminalise buying, less people will buy it, therefore the sellers will be less visible. And you do want to catch the sellers, not the buyers.
I'm pretty sure peer pressure alone can regulate against people looking at child porn, no need to involve the police in it.
I forget where I read it but it was something along the line that penalizing the buyers of prostitution has a larger impact than penalizing the prostitutes themselves. By killing demand you end up getting rid of the supply.
I'm pretty sure peer pressure alone can regulate against people looking at child porn, no need to involve the police in it.