In my opinion there is no way that Buckley should be loosing money on this, in fact for all the work involved I wouln't begruge him making a few quid. organising anything like this is a massive undertaking and until you do something like it yourself you never realise the work involved and the stress to getting everything right.
I suggest that is is £20 flat rate for everyone, thats about half the price we'll be paying to get into Space,DC10,etc over that weekend and by all accounts promises to be a fantastic event. Drinks are bound to be cheaper too
What about an all inclusive ticket that includes all drinks, I think most of us will be on the water with a few beers perhaps

Perhaps £30 all in??
As another suggestion and I'm not sure if anyone has any contacts to do this but it might be worth trying to get a "disco bus" to take everyone on mass to the event since most are staying in either jet appartment area or Figueretas area? That way it avoids any issues with parking taxes,etc?