There are no differences between late production 2008's and 2009's
08.5 added
-Piano Black Trim pieces instead of silver
-Black Cloth inserts instead of silver on Sport models, and Alcantara Suede inserts instead of cloth on GT trims.
-White gauge needles instead of red
-Added two new colors Metropolitan Gray Mica & Crystal White Pearl Mica( REMOVED sunlight silver & Cosmic Blue)
As for how motivated the dealers are, I would say they would probably try to put you in an 08 before an 09, which has better incentives then 09's anyway, it depends on the dealer but they probably won't be too desperate to get rid of them. As spring time is coming the market for performance cars opens up drastically so they probably aren't too worried. BUT every dealership is different so I would just look around see who's willing to give you the best deal!