Did you notice, that if you try to book ex AU for Pacific Blue Happy Hour sale the sale price doesn't apply, e.g.:

From AU:

21Jul08 SYD-CHC AU$229
28Jul08 CHC-SYD AU$203.73

01Sep08 SYD-CHC AU$169 - standard Sale Price
09Sep08 CHC-SYD AU$143.73 - cheaper than normal Sale Price

From NZ:

09Sep08 CHC-SYD NZ$189 ~ AU$149 - standard Sale Price
28Jul08 CHC-SYD NZ$149 - Happy Hour Price (HH icon)

Definitely worth the effort to book separate legs during NZ Pacific Blue Happy Hour...