There will be just 15 seats on each of the flights, which will be operated using tiny Bandeirante aircraft. There's no in flight entertainment (unless you count the in flight magazine), but I've found that just chatting with other passengers more than makes up for that. And if you're looking for luxury hotels when you arrive, this is definitely not for you. Accommodation will be with locals.
The total cost of a round trip to and from New Zealand will be about NZ$2,400 (UKĀ£1,106, US$1,768, 1,199 Euros), which includes the fares from Samoa to Auckland. Conversion rate at 10/10/09 for guidance)