I agree that the OP (and others with similar stories) got shafted when the companies upped their quoted prices. But I do not criticize companies that raise the prices of inessential services or products (such as hotel rooms) when the demand is higher. That's called "Capitalism." If the price is more than you want to pay, then don't pay it.
Another factor to consider is the fact that the profits from Airventure pay for better facilities than one might normally expect. I travel to Oshkosh 3-4 times a year, typically staying in the Hilton. I drive right by the Super 8 to get there, and I rarely see many cars in the parking lot. It may not even exist, if it wasn't for the big summer show (though I believe there are other events in the area as well).
Ron Wanttaja