I've always looked on the GAS page for flights first for probably 10 years now and tell everybody I know the exact same thing.

Air NZ are probably the only airline I've ever come across that sell their cheapest fares on a completely different site to their main booking engine and unless you know about the GAS site you're none the wiser. As I wrote about last year issues like this reflect really badly on organisations like Consumer NZ who spent months criticising Air NZ about pricing and not once mentioned GAS. It shows how little they actually understand about the industry and how misguided their attacks were - actually coming out and telling people that you can't book the cheapest Air NZ tickets on the Air NZ website would clearly be a huge revelation for most NZers when people like you who do fly regularly don't even know about it.

Are Air NZ being evil doing this? That's something I really still can't decide..