Salan, in general, the most expensive books are $9.99, even ones that sometimes can be ordered pre-publication (to be delivered on publication date). Some classics are even less, some free. John wanted to reread Huckleberry Finn, and it was $0.25 (no shipping, of course). And you can get samples of books for free - usually the first chapter - at least enough to let you know whether or not you want to buy it.
The flip side of that is that you might be buying a book that you wanted to read only once, that you could get for free from the library. And, unless you share an account with someone, you can't pass the book on to someone else to read. And not all older books are on Kindle, i.e., Michener, Robert Caro, and a couple of others that I wanted to reread. I do share the Kindle with John sometimes (when I'm feeling very generous
).
I share an account with our daughter. Both of us still read some books from the library - just ones that we don't want to own.