Thanks for that link, which I will add to my favorites.

If buying a new book I always check out http://www.bookkoob.co.uk/ as it gives you the best price taking postage into consideration.

Another alternative is a bookswap. We have one of these at work, basically it's a bookshelf where you put any books you have finished with (others do likewise)and you/they help yourselves to anything that you fancy and return it once done.

My pal gets hers off ebay and there are local freecycle groups too.