Textbooks are so expensive because they are basically a scam. I'm saying this as an instructor - since the first year I started teaching, publishers have been sending me free textbooks trying to convince me to use them in class, because if I assign a textbook students are obligated to buy it, regardless of the cost. It's essentially extorsion. I even had a publisher offer to create a custom textbook by selecting chapters from different books and custom printing them - this means that the books are unique so it's impossible to find used copies! It's a scam.
You won't get in shit for sharing links to textbooks. You have no obligation to buy from the bookstore, and I don't think they care because they can return unpurchased copies. Every student should also know about https://libgen.is/ - you can find a lot of electronic copies of textbooks here for free, especially older editions. I might get in shit for sharing that as an instructor because the legality is questionable, so I don't normally post that on Nexus (although I do say it out loud in every course). I wish I could just post a pdf of the textbook on Nexus for each course but I have to adhere to copyright rules (but I'd share it from my non-work email if anyone ever asked).
Also, what's the link? That's a crazy deal.
Also, if you're fine with digital copies then don't waste money on textbooks. You can find a lot of textbooks for free on Library Genesis https://libgen.is/ (particularly older books or editions - new one might be harder to find).