Note change in components from year to year. 2007 to 2008 could have down spec'd: rear derailleur went to 105 from Ultegra, different crankset, different wheels. 2009 could be up spec'd from 2007 and 2008: Shimano Hollowtech crankset, carbon fiber seat stays, carbon fiber steerer, and general increases due to material costs and dollar exchange rate.
Concur, Hawkfan79. That price roller coaster is odd. I've tracked prices of models that I've had over the past 5 years, and have not seen a price drop between years. Makes me wonder if the price shown for the 2008 is an honest error. The BikePedia prices for my bicycles has been valid.