As the semester ends, instructors at universities and community colleges around the country will begin placing their orders for next year’s textbooks. But not all professors will pay enough attention to something that students complain about: the outlandish prices of the books we assign. Having grown at many times the rate of inflation, the cost of a leading economics book can be over $250; a law school casebook plus supplement can cost $277. Adding to such prices is the dubious trend of requiring students to obtain digital access codes, averaging $100, to complete homework assignments.

Professors love tough questions. Here’s one we need ask ourselves: Are we helping rip off our students?

A good instructor wants to use the best materials, and some of the expensive textbooks are excellent and arguably worth the price. But some really aren’t, especially when there are cheaper or free alternatives of equal quality out there. Basic ethics suggest we have a duty to look for cheaper options before we inflict the $200 or $300 books or the $100 access codes on our students. Professors who write successful textbooks need to think harder about the professional ethics of allowing a book to be sold at exploitative prices to young people.

The root problem is that it is just too easy for us, the professors, to spend other people’s money. Just like doctors who prescribe expensive medicine, we don’t feel the pain of buying a $211 book of uneven quality and no real use when the course is finished, or a digital access code that costs $100 and is designed at least in part to disable the used-book market. The fact that professors choose and students buy destroys whatever power a competitive market might have to keep prices lower. That, and a touch of greed — the author of one successful book has earned an estimated $42 million in royalties — is why textbook prices have increased over 1,000 percent since the 1970s.