Virtual Assistance is still a misunderstood business.
Your business is no different than the hairdresser, the dentist, the doctor, the lawyer, the nail salon, the daycare center. All of these businesses provide a service. They tell you how much the service costs and then you pay it. If you don't like the cost you go somewhere else. You don't negotiate the price.
If people think your rates are too high well, that's too bad for them.
My 2 cents.