Places with no liquor bans (no pubs/clubs)

I’m coming up to Auckland from Christchurch for a concert at the power station, I’m flying up the day of and going home the next day, I’m also on an extremely tight budget with me going on holiday in a few months so won’t be booking a hotel or anything and I was wondering if there’s anywhere in Auckland you can legally drink without spending $20+ on drinks? Sorry if this sounds rather stupid lmao, thanks!