KBB is a good reference point, but it is definitely marked up. I'd also check Edmunds to see what people are actually paying.
Even better, see if you can get ahold of the Black Book, which lists the wholesale value of the car. It is generally several grand less than invoice. Nothin deflates a salesperson like a consumer armed with knowledge about the actual value of the car (they usually groan and mutter to themselves bitterly if you walk in with the black book
)
Dealers should be hungry to unload the 09's which are losing value every day, especially as we approach October -- play hardball, and get exactly what you want.
And remember -- just as the salesperson's job is to get the best deal s/he can, your job is to look out solely for yourself. Don't expect the dealer to be concerned about your finances -- they just want to make a buck and you just want to save a buck.
In other words, don't even bother haggling over MSRP -- get it at or below invoice, keeping in mind mileage and model year. They will still make a nice fat profit off of you even if they agree to a so-called "loser deal" for them -- its all a bunch of BS.
If they won't work out a deal with you that you are happy with, walk out and go elsewhere. They'll probably call you in a day or so to renegotiate.