I love this argument:
Do you think, when buying a Movie or seeing it in theaters, that you should expect to pay half as much for a movie like Toy Story 3 as you do For The Lord of the Rings: Return of the King? I mean, Lord of the Rings is twice as long, should I pay twice as much for it?
If anything people get annoyed when films run too long. I know people who said Return of the King should have edited its ending down a good 15 minutes.
I cannot imagine someone paying $50 to see Dekalog simply because it is 10 hours long.