I haven't bought a paper book that was available as an ebook since 2003. Of course, the selection was pretty sparse back then, but I remember when I used to carry two books everywhere and some days I couldn't resist taking a couple more. It was a hassle to carry a tree around with me everywhere. Now I have a library bigger than my physical library and the entire thing fits on a card the size of my fingernail. I call it "leave no book behind".
I do miss book collecting at library sales and the like, but there are new opportunities to make finds, both with old books at the gutenberg press, google books and with new indie authors.
Welcome to mobileread.