In regards to which timescale? The ASX is the official futures market for the NZEM and the four major gentailers are required to maintain market making positions. If you are just wanting an idea of what prices could be in the next week you can use the WDS on the electricityinfo website.
1-3 months would influence my stay/go decision. Obviously weather limits the predictability massively on that scale but it's always nice to get estimates from the experts