Thank Og… a GQ thread that I can answer!
From my experience at McDonald’s, the product is much cheaper than you may even dream. A patty of meat for a double cheeseburger costed us around 11 cents. The cheese was 3 cents per slice, and the condiments virtually negligible.
All in all, including labor (maybe 2 minutes? I know I can make a double cheeseburger in <12 seconds, but there’s a cashier, and a runner, etc.), I’d bet that McDonald’s comes out 40-50 cents ahead on the double cheeseburger.
As for things that cost McDonald’s a bunch of money to make, I’m betting the McChicken will edge out its other dollar menu competitors.