Given that the paperbacks of the Criticism of Heaven and Earth series (see the side bar) are published by the friendly lefties at Haymarket Books, I have no option but to pass on the Christmas cheer:
A 30% holiday discount on all Haymarket titles is currently being offered through  This sale runs until 5 January.  To receive the discount, a person must enter the coupon code HOLIDAY30 when purchasing a book on the Haymarket website.
In fact, all the Historical Materialism Books Series is available at this rate as well.