What amperage panel do I need for a hair salon?
The usual way for an electrician or engineer to size a service is to do a load calculation that takes into account everything on the service - not just the receptacles at the stations but also the microwave in the break room, the water heater, the lights, etc.  The load calculation takes into account which loads are likely to be on for long periods continuously and "diversity."  In this context diversity means taking into account that you won't turn everything on at once.  

I am a little surprised at what the electricians are telling you but if they're saying the same thing they're probably right.  The size service available to you could depend on a lot of things - the size of the conduit that feeds your space, power company rules, utility transformers, local NYC electrical regulations, etc.