I would highly doubt the fact that retailers makes almost no money of games.
One example :
During the month of January Best Buy had many sales where they dropped the price of a specific game by 20$ for a week before raising it back to the usual price the following weeks.
One week it was Assassin Creed ( which had just come out and wasn't discounted by Ubisoft), another Ninja Gaiden Sigma, I saw CoD4 off 20$ at Amazon for a week too. So all of those games were at 39.99$ for a week.
And I would highly doubt best Buy would sell any game at a loss even during a week sales event so you have to assume they make at least 20$ of profit on full priced 60$ PS3 games ( same for Xbox360 I will assume). And actually I would even expect them to make a little more than that because it would make no sense to sell games like Assassin Creed that were flying off the shelves at the time without making any profit at all...
So if I had to guess I would say they make 25$ or so per game.
Gamestop makes more because they will typically buy your game at 20$ and resell them at 55$. So they make like 35$ per used game and they don't even have to store those games in big warehouses and get them shipped to the store, reducing even more their costs, translating in the end to close to double profit on used games compared to new games...
PS : It's funny how King of Wales claims big electronics retailers make no profit from games where one of the reasons advanced in Best Buy latest financial report for their increased revenue was strong growth in the video games/entertainment sector.
You can find their whole report here : http://media.corporate-ir.net/media_files/irol/83/83192/bby_3q08_ER.pdf
Basically what it says is that Q3 2007 vs Q3 2006 ( their Q3 ends December 1st) their earning per share increased by 71% and the sector which experimented more growth was entertainment software. They mention Video gaming hardware as one factor limiting profit growth, BUT NEVER SOFTWARE.