If you choose a major that requires lots of science classes, you'll spend much more on textbooks over the course of your college career. But why is this so? Why do some textbooks cost so much more than others? Is it printing costs alone that determines value? Is it the material that contributes most the cost?
Material Dictates Cost
Science is a rapidly advancing field, and knowledge is increasing at incredible speed. It takes research, time, energy, and money to progress in certain fields and increase the knowledge base. That cost is somewhat reflected in the price of a textbook. For example, an anatomy book will be super expensive, and a theater appreciation book will likely cost very little. The reason is that anatomy is a rapidly advancing field - there is a lot to learn in an anatomy class. It's a complicated area of study, and the body is a complex machine. Theater, on the other hand, is a part of the arts, and the information load is not the same. That's why an anatomy textbook that's hundreds of pages and includes images, diagrams, and captions will cost much more than a handbook on theater appreciation.
Thicker books cost more simply because they require more paper and ink to print. Additionally, if the book has lots of color images and diagrams, those add significantly to cost. Have you ever tried to get something printed that was a color graphic? It's several times more expensive than if it were a black and white image.
Professors Want Their Cut
Have you ever stopped to wonder who writes the textbook? It's almost always college professors, and they make royalties when their students buy their book. That's an incentive right there to charge as much as possible. But they should make their money if they are the ones producing it, but they can get greedy sometimes. I'm not sure what the percentage is that professors make off textbooks, but I know it's significant for those widely used books.
The one good thing about spending lots of money on textbook is the fact that you can sell your book at the end of the semester for a lot of money.