I would recommend getting your own Carfax or asking the dealer when this Crossfire was first put into service. The specific car you are looking at would have been sold with a 7/70 powertrain warranty that would be in effect for 7 years from the in-service date as well as being automatically transferred to any subsequent owners without any fees. This is important because it is possible the powertrain warranty will still be in effect for a few more months or even longer making the dealer's warranty offer redundant.

At the price you are quoting make sure the tires have most of their original tread. The headlamp hazing is common and will require continuous polishing unless you apply an adhesive film or reseal them. Crossfires are fairly reliable, but... parts are expensive and in some cases relatively hard to find. Many owners use comparable Mercedes parts for shared components since they are often significantly less expensive.

Unfortunately, car-specific enthusiast forums are usually filled with lots of counterproductive posts on how much you should pay. Some of the same people who brag about buying a $9K Crossfire in one post will complain about the vehicle's depreciation in another. Sure there are a few people that pay siginificantly less than the typical sale price but I'm not sure why that should somehow become the maximum price that anyone else should pay. Also, consider where you live may effect pricing. VA, especially NoVa, is one of the few places in the country where the economy is treading water, so pricing may be higher than someplace like FL where there are lots of Crossfires in a dismal economic situation. Look at resources like Edmunds' using the customized appraisal tool to see what others are supposedly paying. That may help you determine whether you are getting a fair price.