You can lend many Kindle books (source: I do it semi-regularly). Many public libraries also offer ebooks.
Your point about paper copies often being cheaper is definitely true, and for books I plan to re-read, refer to, etc., I now default to this. But one of the reasons I like my Kindle is that I can take an entire library with me on a month long trip, change my mind about what I want to read, buy a new book if it comes out while I'm gone, and sample things I'd otherwise need to go into a bookstore to find.
