I'd imagine the on the door charge is to offset any potential loss compared to showing a football game, plus they'd have had to probably pay Icetime to show the game publicly. Im sure if they hold more of these and they are well supported the on the door fee may go, then again im not sure what the one off cost to show a game publicly is so it might just be to cover that. I know they pay to have Sky etc but that would have been accounted for in there yearly budget whereas one off hockey games are not.