That comment is only in relation to 4th gen turbo legacies as far as I'm aware (others can confirm). Plenty of tuned Auto 3.0s I believe.
It may be 299 AUD, but you'll need to get it shipped to NZ and then installed which requires cutting your stock headers out and getting this welded in. I think it's safe to assume you would spend 1k NZD, but others who have actually done it will have a better idea.
3.0 would be fine for a daily in New Plymouth I reckon, traffic can't be that bad down there;) My 3.0 chews through traffic in stop-start Auckland peak traffic, but for motorway/open road cruising it is fine on gas.