Why are there so few braille books?

Short Answer
It is more time consuming, and expensive, to create a braille book. It requires a braille printer, heavier weight paper, and a transcriber to convert the written book into braille format.

Detailed Answer
Gaining the legal right to reprint content and the cost of translating content are the two primary reasons very few books are translated into braille. Braille books are created by taking existing content, translating it into braille format (either manually or by using translation software), having it proofread to ensure the translation was accurate, using a braille embosser to “print” the braille onto specialized braille paper and ultimately binding it to create a finished book.