I have purchased only one new book in about 4 or 5 years, and that was off amazon last year. I download epubs off the net - sharing sites, and some free books sites.
I did try to purchased one epub but the transaction wouldnt go through because i guess my CC is from NZ and i was trying to buy from here.
But i usually buy real books from second hand stores, especially from salvation army stores in aus... i would buy 10 or so at a time, for a dollar or 2 each. Then bring here and read, then give away/swap when finished.
The other good place i get books is from a friend who works for an airline, the books that are left on the plane are put into a crew library, so he will grab me a few when he comes down this way.