I agree with Wilkie! I think they could easily double the entry fee without any fuss. Although I don't think that it will necessarily follow that they will reduce what they charge charities by the same amount. They could leave the charity fee the same and have more funds for their own foundation. It'll certainly be wasteful to have a big gap between elite and fancy dress runners.
Perhaps the GFA entry could be priced higher as a premium for it being guaranteed and secure, rather than a lottery...
I also like the idea of the age grading, perhaps at 65% (so as not to exclude me!) but I think that this would be less workable from an administration perspective.
Does anyone know how much the international runners get charged to run the VLM? For Italian races (for example), they charge more for non-Italians that locals.