Is there a way to save my students money on a textbook? I'm considering requiring a textbook that sells for $140 on Amazon.  Used copies cost $95 and up.  I expect about 60 students to take the course.  Our students are not wealthy, and some will skip buying the book (and their academic performance will suffer) if they feel they cannot afford it.  I'd like to find ways of saving my students money.  

One idea I have is to see if it's possible to get a bulk discount and pass the savings on to students.  Another idea is to set up an Amazon affiliate link and refund the kickbacks to students, although I'd probably be liable for income tax.  (Of course, I'd request approval from the Provost's office before trying something that could appear to be profiting off of students.)

I live in the United States, the publisher is Pearson, and there does not seem to be an international edition.  There is only one edition of the textbook.  (For other classes, I've saved the students money by letting them use an earlier edition.)  I have been unable to find a textbook of comparable quality that is significantly cheaper.

Has anyone tried any of the above ideas or others?

RESPONSES TO COMMENTS:

Why require a book?  I do not always require a book, but I think it is necessary for this course in order for students to learn the material.

Why not write my own book or lecture notes?  I have co-authored a book on a topic on which I am an expert and made the book available for free online.  I could not do as good a job as the expensive textbook's authors in this subject matter, especially because I expect to only teach this course once.

Why not use a free online textbook? I was unable to find a free book that did a good job covering the required material.

Why not encourage the students to find an illegal copy online?  I consider copyright legitimate and would not encourage my students to do something illegal or unethical.

UPDATE:

After I assigned the Pearson textbook, a student discovered that it was available for free online through the local public library. I immediately informed the other students of this option and let them know how to get a public library card. I will always know to check this option in the future. It had not occurred to me that a publisher would allow a popular textbook to be made available for free in this way (with no limit on the number of simultaneous viewers).

SECOND UPDATE:

I learned that ACM Student membership, which is $19/year (with possibly lower rates in the developing world) includes access to Safari Books Online, which has a book I am requiring this semester (in the Head First series) and has many other great computer science books (typically used by developers, not as textbooks).
An easy thing to do that can be very helpful to your students is to put a copy of the textbook (or two or three copies) on reserve in the university library.  Students can then photocopy critical sections of the book (e.g. the homework exercises.)  This is particularly helpful at the start of the semester when students are waiting for copies of the book that they've ordered online to arrive.  

If you have control over the choice of the textbook, you should consider moving to a cheaper book or even an open educational resource (OER) that is completely free to students.