7. Hard-to-find antique or public domain classics are often free!
Are you a sucker for classic lit? Often times, you can find classic texts — including hard-to-find antique texts — in ebook format for free download.
If you’re also an English major, this saves HUGELY on your book bill — I know from personal experience. (And that free version of von Goethe’s “Faust” from Project Gutenberg is still my favorite over any I’ve read since.)