I rushed to buy Sunday tickets early Wednesday morning. They said tickets would be released at midnight, but it took a minute or two after midnight for them to be available. I recommend that older children purchase seats, even at half price, because the carriages are incredibly crowded. The free time at each attraction is quite ample, but restrooms can be a challenge. Girls, in particular, had to wait in line for a long time.
The only additional charge is the return shuttle bus fare to Tuanshan Mingju, or you can hike down the mountain. It's not expensive, only three yuan per person. Overall, the experience was good, but it wasn't as clean and inviting as advertised. It was quite crowded, and there were a lot of people smoking at the station.