How are the plane tickets? From shanghai to Nanjing how much is a plane ticket for example?

There is only one direct flight from Shanghai to Nanjing.
However, I cannot estimate the fare exactly because the price is changable with seasons.
In usual time, the ticket price costs CN500 to CNY 600 for the economy cabin.
The 2 cities are very close. Taking high speed trains or bullet trains from Shanghai Railway Station or Shanghai Hongqiao Railway Station is more convenient. You will get to Nanjing in around 2h and a second-class ticket costs CNY95.5 for bullet train or CNY134.5 for high speed train.