Well you have to keep in mind that everyone dosen't get the same price per unit, even when buying from the same dealer. It often depends on how many units you are buying and too on how often you are buying from a particular vendor..
Not all stores even sell for a 'per unit' profit.
Alot of the larger chain stores don't even make a profit on the console. They are paid a 'shelf fee' by the manufactor, such as sony, or nintendo to allow them to sell the units through their chain stores..I know that stores such as walmart and sam's club are paid a $50,000 shelf fee for items like playstation and xbox. Those units are put on sale for the manufactors suggested retail price and sold at that price and sometimes lower. It dosen't matter to the store what the unit sells for as they are making their money from the 'shelf fee'....