Try the following car buyiing service
http://www.metrocu.com/services/AutoBuy.html
I was able to get couple of hundreds off the MRSP but the trade in for my piece of *#&^ ML320 was way too low, therefore I did not buy from the dealer they use. Mind you, sometimes you might need to pay a little bit more to buy from the dealer that you will be servicing your vehicle because if you have a problem they're more likely to help you if you buy the vehicle from them. In my case there was 3 dealer that I considered: DVP, Erin Mills and Oakville. I choose Erin Mills because of their service hours and recommendation from a neighbour. I paid MRSP but they give me a reasonable price for my use ML320.