If you can get to SYD on the Zed there are an untold number of bargain flights across the Tasman. The arrival en-masse of the LCC's have meant QF/NZ's stranglehold on high fares trans-tasman has basically vanished. Good deals are often found with PacificBlue, Jetstar, Freedom as well as QF and NZ themselves. THen you also have the 3rd country carriers like Emirates, MAS, Aerolineas also flying between ports of the two countries with traffic rights to sell. EK in particular often have very good prices.