You make your budget cuts wherever you feel like making them. If a 100 dollar ticket becoming a 105 dollar ticket is a deal breaker for you, that is your choice. Spending on entertainment is clearly a discretionary spending item for everyone and everyone has their breaking point. I rarely buy concessions at the arena either. I do however support the arts in the city and they are a foundation in all great cities.
People already pay 8% as an entertainment tax in Cleveland, 12% in Chicago and 5% in Pittsburgh for example. This is not a new concept for any city.