Cruising costs

I am keen sail a 40-50ft boat to cruise the Med next year, but can find no information on berthing costs in the Med or even just information on a ball-park budget for running a boat.  Can anyone tell me what it would cost?  Or where to go to find out?

HotSailor

Well, we are thinking of going from Holland to Rome, Italy starting in April and fetching up in Rome July-ish.(-going across France instead of all the way round?  Don't know how possible this is in a big boat....)  Then we would want to stay there for about a month, and then do the French and Spanish coast including Mallorca, ending up in Gibralter for the winter.  This would be in a 50 footer. 

On all the Italian sites that I have explored so far, you get all the info about the ports and marinas, but no cost details!  Surely the cost is just as important as the location of the toilets?!  I have sent off enquiring emails as well and had no reply...what do people do, just turn up and hope for the best?  That is too loose for me, I need to know the likely demands on my budget so I can plan!  How do people do it?

Thanks Jon!

HotSailor