Hmm ... I fancied reading on the train today on my way back from my New Year family visits so I bought a copy of The Social Animal at the station. It was £8.99 in paperback, and would still have been £7.50 from Amazon, but it is available for £1.99 for the Kindle!
It is a very chunky 550 page paperback (including references). Now, the man in front of me was reading a book on one of the new keyboard-less £89 Kindles so I was able clearly to see the difference in size between it and my large paperback. I could also see how clear the text was on his Kindle, and how quick the electronic page change was. I was impressed.
I know that some books are not much cheaper for the Kindle (or sometimes even cost more than the paper editions!), but I reckon that it wouldn't take more than a couple of years to save that £89 by buying bargain Kindle books. I think I'll buy one once I've caught up on my backlog of paper books.