You'll find that upgrades at check in never happen in Australia or New Zealand. As Matt mentioned above, they do offer upgrades in the form of an email just prior to online check in.
On most of the long haul flights from NZ or AU they typically don't offer these upgrades as Business class is often full but on the flight from CHC-SYD and SYD-CHC you'll get them for around $400 (oneway).
It's worth noting that this $400 upgrade doesn't include the limo, lounge access or extra points. Given return services often however around $400 on this flight I've never been able to justify the price. As a point of comparison VA's bid upgrade starts at around $150 (the low offer) on NZ routes.