I think you've got the right idea, but your math is faulty. As someone said, the claim is usually "pennies a day". So let's say a channel wants an extra 50 cents a month (just to keep the math easy). Now multiply that by all the subscribers.
BUT, although you mentioned it, you didn't take it into account. Your bill goes up $5/month. Now multiply THAT by all the subscribers.
While channels claims of "pennies a day" is simply spin, so is Dish's claims of "fighting to keep prices low". If they were fighting that hard, wouldn't you expect to see a drastic difference between Dish's prices and their competitors? And wouldn't that difference increase over time since Dish keeps "fighting"? Why does the price difference stay pretty constant?
I was under the impression that a local channel might charge let's say .05 cents per month for retransmission.
The reason why you have the $5 charge because Dish pays for the fiber back haul to get the signal to Cheyenne Wy or to whatever uplink center they are using. Then you got the cost of a $250 million dollar satellite where you are using an entire spot beam transponder or 2 to serve 10-50 subscribers in a specific DMA, where as a conus transponder has a much lower per subscriber cost.
Look at it this way. If we didn't have locals, Dish would not have an eastern are set of satellites.
IMHO, the local channels would be better off giving up their terrestrial broadcast licenses and become cable networks. They could charge more money and wouldn't be subject to as many rules and restrictions.