Hi All,
I tend to let students (and others) know about free or special offer books, whenever I find them available. Many of these are ebooks, rather than physical books, but if you can cope with the format then it does enable ministers to build up a library much more quickly and cheaply.
FaithLife (American publishers) offer free ebooks most months, and you can sign up for their emails. This month's offer is at:
https://ebooks.faithlife.com/free-book-of-the-month
All best wishes,
Paul