I was hooked big time on the first 2 games in this series, but when I played 3, I just didn't "feel" it. I think the 3D killed it for me. A game like this doesn't need to be in 3D, IMO. With that said, I never played any expansion pack, and no longer have the main game, so I might pick it back up at this price and try it again. Maybe it will just take time to get into it, I don't know.
BTW, I think you could charge admission in 2, it just depends on the scenario. Some forced you to keep it free and make money by other means, some didn't. Or maybe I'm confusing it with the first game, but I thought they were largely the same in that regard.