As others have stated:
$2,500 customer cash
$500 dealer incentive
Other info:
Base Dealer cost including Dest $16,313
The dealer also has a $338 kick back of some sort - I won't reveal my source on this one
So, $16,313 - 2,500 - 500 - 338 = $12,975 actual dealer cost. Interesting that this is the exact price Jim Ellis Mazda (Atlanta area) is advertising for base P5's isn't it.
Now you know what number to start from. Go to Edmunds.com to find the dealer cost for each option on the car you are looking at. Simply add these to the base of $12,975 to get the true dealer cost of the vehicle.
Now, the salesman should make something on the sale. Afterall, that is their only source of income. $300 is fair in my opinion.
A tip on financing. I always use PeopleFirst.com (now capitaloneautofinance.com - both web addresses lead to same place). I recently got a loan at 4.09% for 60 months for the purchase of my P5 from them. They will FedEx a certified blank check to you valid up to the amount you qualified for. This makes things extremely easy and can actually help get you a good deal from the finance guy at the dealership. The finance guy doesn't make a thing from a sale unless he arranges the financing. When he sees that blank check he is going to do anything possible to attempt to beat it. The best deal he could offer me was 3.59% financing for 60 months, but it required that I buy an extended warranty (7 years/100,000 miles) for $1000. This equates to about $14 more a month and about $880 over the life of the loan. Not a bad deal, but I stuck with my PeopleFirst as they have ALWAYS been great to me. Finance guy was pissed.