I have been passing old books on to Libraries and Goodwill for a number of years because I've never had enough room to keep them and I know I won't re-read most of them. I only keep hardcover copies of my favorite writers (mostly Stephen King).
I hate having to buy a paper book but if I do, I try to find the best deal (eBay).
If you love hanging out in books stores, take your Kindle with you and download any interesting books you find (if available as ebooks) and buy paper copies of those that aren't or that you just want in paper. It's not an all or nothing proposition, you can have both.