Oceania (Australia, New Zealand & the South Pacific) - 24 hours in Auckland

I arrive in Auckland on 23rd November returning from the USA to Australia.
I have never been in Auckland. I think I arrive about 0900 (QF26) and have until 0700 the next day for some free time. I don't want to spend a bucket load of $$ , so is it better to stay near the airport or head into the city and spend the day away looking around? Looks like the transport to/from airport to cbd is expensive. Are there any spots closer to the airport that are a "must see"? Or, do I just bite the bullet and catch a taxi/bus into the city and return early early, (arrive at airport by 0500) bus/taxi back?

There really isn't much to do near the airport and the hotels there are not cheap. AKL airport does have a new capsule hotel, but I think it is priced for short stays so maybe not cheap for overnight and certainly not pleasant. The bus to CBD is pretty cheap by world standards, and lots of free attractions as well as cheap food etc. Seems crazy to consider staying by the airport for such a long layover (at least imho).

Would the bus be able to get someone from CBD to the airport with plenty of time for a 0700 flight ?

Would the bus be able to get someone from CBD to the airport with plenty of time for a 0700 flight ?

Yes. The airbus runs 24/7.

Yes. The airbus runs 24/7.

Thanks, you guys settled it, Will head into CBD. Thanks Kiwi flyer on the bus info. Looking forward to my first visit to Auckland.