I buy mine from Martingales in pdf form as I live in Finland so I save the shipping fee . They have all books in print as well, free shipping on over 40$ purchase. Every week they have a Sale, Weekly WOW!, some books for 40% of their regular price. In fact I just ckecked their link and I'm going to order one on patchwork jackets for under 8$!
http://www.shopmartingale.com/on-sale.html