As a special limited offer... I have some 2009 Calendars left. Obviously I don't expect anyone to pay full price, but I'll offer them for 25 each. Sure, you can't use them as a calendar, but for a collector's item, or just to put the big glossy pages up on the wall as posters, someone may still want one.
If you want a 2009 calendar thrown in with your 2010 one, just pay the extra 25 and I'll know.
If nobody buys them, it just means I have them to put in the archives.