As far as you specific question about €... I have no clue.
But I would say well paid...
xxx
Because your duties will be quite involved in many things...
It is likely that when the potential customer calls, you will answer questions, schedules, and cost...
So, you are a salesman... Then...
Quickly check if Nice airport is closest to Monte Carlo... is it open tonight...?
Call the crew, to see if available and ready in 2 hrs time...
Call the customer again, and confirm, ask Visa card number for billing...
You probably will have to make all arrangements, route, flight planning, met reports, fuel, handling...
Possibly make hotel reservations/crew transport for destination...
Order catering, and the bottle of Dom Pérignon and Chateauneuf du Pape...
And help the crew load baggage when passengers arrive 3 hrs late.
Try to get the tower to make an exception for the curfew time limit.
Park the car of the customer... in a safe place...
xxx
So it is likely to be well paid, especially if working at times on saturdays and sundays, or at night...
Receiving calls at home if nobody is on duty at the airport.
xxx
Happy contrails.