@sneak Also, I prefer to buy directly from the publisher, if possible. E.g. O'reilly, pragprog, packt, Manning, apress, etc sell (or used to sell) books directly.
Sometimes writers sell direct too, e.g. via gumroad or on their own sites.
@berkes i specifically hate creating accounts and dealing with payments to multiple sites/databases, so this approach is a nonstarter. i want a single non-amazon vendor to deal with who has a huge selection so i can buy all my books there.