I personally consider textbook publishers to be somewhere between an unethical business and organized crime.
They rip off your students, so don't feel bad about getting as many copies as you can squeeze out of them, and then some more to give to your students.
Most books are printed overseas anyway, at a cost of ~$5 each.
You can imagine how much they make on a single book.
Elsevier has roughly 7 billion EUR revenue and a profit margin close to 40%
If there is any alternative, I try to go for books that are cheaply available to the students, and for books that don't randomly change the enumeration of homework assignments to make older editions useless.
I think it is time for us to push back in the interest of our students. Our department decided not to go with books that needs to be 'registered' online to be usable. That was a good first step.
I wish university libraries would provide textbooks. They have a much larger buying power, and would end the textbook scam very quickly.