For shop you should read charity/secondhand or carboot sale! I rarely buy a book new, if I can possibly help it. I usually spend £1 or under, and often it is passed around all my friends before being sold on. I also use a great website called greenmetropolis.com where you can recycle books buy buying them for £3.75 P&P free (obviously UK only) then sell them on for £3. Also ebay is excellent, and I have the advantage of a best friend who loves books and has lots of disposable income. I do buy new, but usually only if it is an author I adore and I want to read it the moment it comes out (Phil Rickman or Jasper Fford for example) or I've been given book tokens, which are the motorway to my heart.
I think maybe I shall make this the year I read War and Peace then. I've listed The master and Margarita as one I'm looking out for on Ebay.