I picked only buy ebooks, although I have bought textbooks and the like from bargain used books stores in the past few years.
I started reading ebooks on my palm pilot way back in 2002 or 2003 and I've never looked back. I have bins full of unread paperback novels that I store year after year because I can't bear to part with them since they represent hard earned money that at the time I thought was well spent.
But now, it is just too natural for me to grab the ebook than it is to read a paperback novel. I'll even read on my pc before I pick up a book. I'm the opposite of most people in that real books make my eyes hurt.