We don't have Class 'C' in the UK. However, the Class 'D' we have (the nearest equivalent) no charges are made.
I have flown VFR in class 'C' both in Eire and in the U.S.A - no charges are made there either.
I think you'll find the only country which has any kind of route charging for VFR flights is Italy.
From my own point of view I think charging for this sort of thing is a dangerous road to go down. All you're going to do is prevent traffic talking to yourselves and increase the chance of an unknown penetrating Controlled Airspace.