Textbooks=Misery

Why do they cost so much? How can they justify charging 160 dollars for a book, buying it back for 60 dollars, selling it used for 95 dollars, buying it back for 40 dollars, selling it for 95, buying it for 40, selling it for 95 and then not buying it back because there is a new 160 dollar edition that has the only change of having a more up-to-date cover?!?!?!?!?! How much money are they making off of that one book? 160-60+95-40+95-40+95= 305 Bones!!! I need to get into the textbook business. I've been in bookstores. I've seen big books. They don't cost 160 dollars. They definitely don't cost 305 dollars. For 305 dollars, you can get an entire set of encyclopedias! That's 32 hard cover reference books!!!! If regular bookstores can stay in business selling books once, and only once, for a reasonable price, then the textbook department must be making bank. I'm frustrated. I need to just go to sleep and forget about it.