And what would you recommend to be a reasonable and fair cost?
What he is saying is that it is user pays vs ratepayers pay.
At the moment the users are effectively paying for the upkeep and improvements of the stadium. The stadium receives no additional funding.
Therefore any decrease in price to the nix or to carparks will probably mean the ratepayers will have to chip in to make up the shortfall.
Specifically to carparks, people are obviously paying it, presumably if they could make more money by reducing the price they would. Therefore if you reduce price, you reduce revenue, and once again the ratepayer would possibly have to cough up the shortfall.
However I do believe it is fair that the ratepayer should burden some of the cost, and the stadium should get funding. As much as user pays does sound fair, Wellington city does get a benefit out of events being held at the stadium as well, so they should also contribute in my opinion.
Edit: to save confusion id like to add that when I say 'revenue' I don't mean profit - all revenue goes back into funding maintenance and improvements of the stadium.