I liked to read them too when I was little. I had an obsession about weird diseases and could only find them in encyclopedias and the adult section of the library. I knew way more about small pox, elephantitis, and syphilis than any kid should ever know. 
You know, when I was a little lad, in the second grade I think (because I have some unfond memories of that teacher, so it must have been the second grade), I decided to make some money, and took three books out of my father's library to school.
One of them was a very large book with transparent plates, showing the layers of the human eye. Another of them was a small manual about dealing with women in labor. A third was about contagious diseases, profusely illustrated with photographs.
At first, I charged classmates five cents a peek for any of the three books.
Then I had to adjust my rates for the market.
A look at the human eye was still five cents, but I upped a look at the contagious diseases to ten cents, and oftentimes had to offer a look at the naked women in distress as a "free bonus" for looks at either one of the other two books.