A big part of money saving is reusing and recycling and what beter way than with used books! I saw this site a few days ago and thought I'd share it with you. Never pay full price for books again, and in addition (and what makes it better than something like Amazon sellers, is that delivery is totally free in the UK!)
There are special offers on loads of books in the Deal of the Week section, with prices from £1.99.
The books from the children's section include story books, picture books, activity books and early learning material, children's and teenage poetry, anthologies and annuals, children's and teenage fiction and true stories, general non fiction, educational material, reference material, personal and social issues and stationary.
I posted this idea for a book advent calender recently. It's probably a slightly expensive for a 24-day advent calender to start with, but if you use it year on year, it'll be a great memory.