Use 'extortionate' to express your dissatisfaction or disapproval towards very high costs. They're charging extortionate fees for basic services, which is unacceptable.
Pro Tip 2/3
Emphasize Unfairness
Apply 'extortionate' when you believe a price or demand is not just high, but unfairly so. Paying $15 for a cup of coffee is absolutely extortionate!
Pro Tip 3/3
Controversial Usage
The term can sometimes seem offensive, so be cautious when using it to avoid insulting someone unintentionally. Calling the artist's commission extortionate was rude and caused a heated argument.