approximative cost of agency fees

Hello everybody,
I'm 17 years old and I would like to work in the world of yachting.
first of all my english is not really good so please be comprehensive and I don't know much things about yachting..
I need this information because I'm trying to make a report for my studies and maybe my future job.
I would like to know how much it would cost for a yacht to berth in France for example.
I presume the cost depends of the port but I'm particularly interested of the cost for the port of ajaccio (corsica-France).
Someone told me that it's necessary to have like a port agent and so to pay agency fees.
Can someone help me please..
Thank you in advance.