It seems like the main point here is how everyone is representing and marketing a product. Doesn't matter if that is a movie, music, book or a service. If they are unable to attract your money maybe they have to reconsider their strategy. Just putting a picture with a short description and a price is not enough these days. And something else... It's not only about the money. Paying for a service saves your time. I prefer to give money to someone and use the saved time to make more money than I gave.
And excuse me but most of the books are overpriced. You pay 100+ bugs for a pdf file and what?... No printing house. No paper and ink. No transport cost. They are not using a storehouse, no workers with their salaries, insurances etc. moving goods back and forth. It's just a website and a database. The HDD space is cheap.
And... I am shocked. $300+ for a textbook?!

Where I live this is more than half of one's salary. In such a circumstance it's not about the moral at all but the money.