I think the problem is that you're considering a comparison between a total budget and a single line item.
---------- Post added 2012-11-19 at 09:45 PM ----------
If we're trying to predict rational company behavior and determine whether there will indeed be a shortfall, there's no reason to treat an opportunity cost any different than any actual loss of money on the making of that product. I know this offends people's sense of justice, but I'm really not clear why.