Buying a 2011 Dodge Durango, and saving $6000 off of MSRP.
I would use the Car Cost Canada "Wholesale Price" as your starting point as it appears that those prices are already above actual dealer cost. If you go above the CCC Wholesale price, I really wouldn't go above by more than 2% to 3%.
For me I didn't need to use the Wholesale Price Report as I'm eligible for Employee pricing on Chrysler products. This is how I know the prices are already marked up. I signed up for the service as I was also considering several other manufacturers