Have you seen the book advent calendar you can do? Its quite simple, just wrap up 12 books or 24 if you you celebrate advent for 15 days. Open one a night to read with your little ones.
I like to put a book or 2 under the tree or in their stockings, just as filler gifts so this works out a great deal.
The Works have an offer to buy 10 books for just £10, making each one just £1 and giving me quite a few cheap gifts.