First, unless you are in a very specialized field, there are surely several books that cover the topic you are lecturing. In the interest of politics have an official book, but in the interest of time offer alternatives. Your students, or the good ones, at least, will be able to use whatever book they can fit in their budget, including previous editions. Especially if you're teaching calculus.

Second, if you are grading homework then produce your own problem sets. You already have to do this for exams, which means you know what you expect your students to learn, so you may as well produce the problem sets as well. At the very least indicate what types of problems a student should practice on so they can follow along in the book they do have.

Third, thank you for lecturing. I know that lecturers hate the raw deal with textbooks as well.