Charity Or Store?

I used to only buy books from Charity shops. It made me feel like I was helping and doing a good deed and I also got something out of it. But as soon as Waterstones brought out their card, I haven't stopped shopping there. The collection of books is great and I always end up buying a book from a completely different genre to what I went in for. It's like going into another world. I find it just as private as a library, but it just has a lot more books than my local library *X*