The price of books that aren't new are a little high. You're looking at paying the same for the Kindle version as the in-print paperback. I'd find a price of $5 for an electronic version of an $8 paperback reasonable.

The paperback obviously has the advantage of being able to be read by two (or more) people with a single purchase as well. It's not tied to your biometric scan. The Kindle books are tied to the one device right?