one problem there, and with the parents reasoning... Most text books are NOT paid for by the publishers. The authors (normally professors at a university) write the book while being paid by the university. The university wants their name on the book (just like they want their professors names on research papers) as it helps the university's rankings (you know those rankings everyone bases college choices on even though they say absolutely NOTHING about the quality of the teaching at the schools). I'm sure the author of the calculus book is doing pretty well because of book sales, but I'd be surprised if he gets more than $10-$15 for each book that sells. The publishers however are raking in the money, and the college students are paying for it twice, once when they're paying professors to write the book, and again when the publisher sells the book. Then the publisher does their best to screw over the students even more, by forcing professor(s)s to sign a contract saying they'll make new revisions of the book every 2 or 3 years. Sure in some fields this makes sense, but I don't think there's anything new being taught in calculus today that wasn't in a book from 10-15 years ago (likely more, although some changes are made to keep the book "relevant" with engineering disciplines, etc). The sole purpose of that is to kill the used book market. Professors can no longer teach a class using the old book because new copies aren't available, and students can't sell/use an old copy, as the problem sets are different (normally that is the main thing publishers want changed in a book).
Of course, on that note, I remember paying ~110 for this same book new 10 years ago, I guess inflation has been terrorizing the book market.