2010 calendars just plummeted in price. But for the best wall calendar value, wait till they're practically giving them away after mid-year. Then print your own personalized calendar with pcal and tape them in.
It's a silly way to save money, but wall calendars are a pretty silly way to spend it.
(Even sillier, but possible: save your calendars. Your 2009 calendar will work again in 2015, and a 2010 calendar in 2021.)