This is one of those things you can only find on the web. A discussion about the economics of movie popcorn over at Kottke. There are currently 92 comments discussing the pricing structure and profit involved with movie popcorn.

Jason set the discussion:

This "Super Combo" costs a lot less than ordering a L popcorn and a L soda separately from the menu but often it will actually cost you less than a L popcorn/M soda, M popcorn/L soda, or even a M popcorn/M soda (?!??). Why such a steep discount when the theaters make so much of their money on concessions? I've developed a few theories over the years but would like to hear your thoughts before sharing them.

I have a similar retail pricing/sales story to share about convincing people to spend more for the same product. I just might do it as a podcast.