Ask him if he's adding in "market value". Apparently, alot of "market value". My dealer tried to add $5000 ontop
of the $22k msrp (no XM, OnStar, or side airbags) and offered $2000 less for my trade-in than it's book value. I didn't pay the extra $5k (although I did eventually settle for msrp, should have just left and come back later) and didn't trade in my old car.
They just know you want the car pretty bad. Tell them they're crazy, list a bunch of other cars you could buy for that kind of money, and tell them you'll just go to a different dealer or wait for the '06 model. Also, they should have given you a price before you ordered and placed the deposit. I'd at least email Chevy
about the dealer and let them know your not very happy. I've used that form to email Chevy about my dealer and got a reply the next day.