Nowhere is price gouging so clear as in the case of textbooks. You have almost perfectly inelastic demand, and a single supplier. You don't need to be an economist to figure out how that one's going to work out.
This semester, my econometrics professor had a professional publisher 'compile' his seminar notes into a 'reader'. This basically meant printing out the pdfs and putting them in cheap binding, the kind that you might get at Staples for a negligible sum. He was shocked when they ended up costing almost $100 per copy for the student, since there was no copyright/licensing in question - they were his own class notes.
If a college student told me that they spent over $1000 per semester in textbooks, I would have no trouble believing it at all. Used books are not always available or viable. Workbooks are less common, but now publisher have 'access keys' that they are using to force students to buy the new books. My professors have always been understanding when I refuse to do the online exercises that require the access keys (unless they send me unlocked copies), but I can imagine not all students are so lucky.
I'm also fortunate that my classes (CS, statistics, economics) tend to have one textbook per course, and they usually aren't so dependent on the in-book homework problems. For CS in particular, you can often use online books/tutorials in case of the text, depending on the class.
But for my friends in humanities-based classes, with perhaps ten overpriced books for a course? I pity the fools - or rather, I pity their empty wallets!