In 2019 they were $1, but it depends on the owner. They might judge by population, economic strength, tourist attention, what they paid, advertising potential, personal greed etc. Some will put the price up if people are interested, others are flexible.
@46903 It looks great, only one minor problem, you left 'your city' in the description. I hope the advertising works out 🤞 That reminds me that I must do more work on my own cities 😏