As far as I know the only show they charge for is the Cirque Dreams & Dinner - because it is a dinner show.
Here is a funny story, though. NCL took a group of us to the Cirque Dreams offices near Palm Beach and we all saw the Epic show and thought it was all good - but when we saw it on Epic it just fell flat - no one I was with liked it at all.
Now, one big difference was that we could not see as well on the ship as in the studio - another difference was that the ship renderings had made the ship "circus tent" look huge, but in real life it was tiny. When they strung up a "tightrope" it was a "sag-rope" literally, with the guy standing on it sagging from two points about 8 feet apart - not very impressive.
Anyway - I was actually surprised the show was kept for Breakaway, but it was. But they really jacked up the price from $10 and $15, to $29 and $39 (or something) for back row /premium seats.
Sorry, but I don't think that would be fair price for the show I show on board Epic. Maybe this one is way better, I don't know. Maybe the theater is bigger (it looks bigger on the floor plans but NCL told me it was the same size).
I dunno - but the price is for the dinner, not just the show, but I agree it is kind of a sneaky way to get you to pay for entertainment, especially when the food was not that good.