I agree that some of these prices are outrageous and if it wasn't for the rich investment bankers and businessmen who have more money than sense, then these prices would have dropped a long time ago. Most of these girls know that these investment bankers and rich businessmen will easily pay that amount of money and therefore they keep charging that amount.
Secondly, these girls talk to each other which creates a culture not just in habits, but also in pricing which they all copy.