Oh, my school changes books every year, and even every prof (the prof teaching in the fall might like one book, while the prof teaching the same course in the winter may prefer another).
The point is,* it doesn’t matter whatsoever*, unless of course you were subject to mandatory bookcase inspections and/or had a gun to your head.
Edition 18 (150$) of a book won’t be different from Edition 17 (100), not by any extent that will affect your education, and I'd wager that for most undergrad courses, Edition 1 (2.99 on Amazon marketplace) would suffice. Anything missing can be found via Google, because so many schools have on-line material anyways, and every undergrad school on the continent teaches the same damn stuff. Heck, a completely different book by a different author on the same topic will do. Your prof wants Adams for Calculus, and you own Stewart? Doesn’t matter. Riemann sums haven’t changed in hundreds of years, derivatives and integrals still follow the same damn rules, and both books cover hypervolumes. I used Hibbler for statics when my prof taught out of Beer - didn’t matter. Half my biochem classes used Stryer, the others used Lehninger…I think you can guess; it didn’t matter. In fact, you might have the advantage, because a lot of profs copy certain things word-for-word out of textbooks, and having a different book allows you to read the same thing in different words, and therefore understand it better.
Have the confidence in your own ability to learn, in your ability to navigate a Table of Contents and/or Index, and “stick it to the man” by saving hundreds of dollars a year that are much better served in paying for rent/food/clothes/beer/messageboad subscriptions/whatever.
I think some of this could apply to non-science/engineering also. You might have to be careful in the case of translations, but Shakespeare, Dickens, Wells…a whole bunch of stories and books are available for free via things like Project Gutenberg. There’s no point buying a book for even 10$ when you can get it for free.