Car Dealerships in Dubai/Abu Dhabi

I'm moving to Dubai very soon (this coming Saturday) and was wondering if there are any particular dealerships I should visit (or avoid) in terms of picking up a car. I'm looking at picking up a Porsche 2008+ Carrera(S) or a 2007(+) GT3 if the price is right. I've visited Autotrader UAE and there seem to be quite a few nice cars available which isn't entirely surprising given the current environment. A lot of these cars are listed for sale at "Best Offer" and I'm curious if anyone here has insight as to the level of discount once might reasonably expect to receive on gently used cars. Any and all other tips will be very much appreciated.

Thanks,
Danysh