"So we are not dramatically spending huge amounts of money in comparison to some of the campaigns we've seen."
He said although it was more frugal, New Zealand would still be spending millions of dollars over the entirety of the campaign - but the pay off was worth it.
"It gives New Zealand engagement and relevancy with a lot of countries round the world. It helps the development of your country."
He said that could also result in a financial benefits in the long term - by building links with rapidly growing regions such as Africa which could result in trade relationships.
"We at the moment focus on Asia, that makes sense. But if you roll the clock forward a decade or so, I'd be surprised if New Zealand wasn't doing a lot more business with Africa."
He said there was little that could be done about others using aid to try to secure votes and it would be hard to police if any rules were put in place to govern conduct during such campaigns. While New Zealand did not tie its aid programme to an obligation to support it, he was hopeful that those countries would, although the other countries also gave aid to many of the same countries.
At the Pacific Islands Forum last month, the leaders did agree to support it - and the Pacific is the region most of New Zealand's aid goes to.
Early this morning, Mr Key spoke at a breakfast meeting hosted by Samoa's Prime Minister because New Zealand is helping fund Samoa to host a Small Islands Development conference, including providing a cruise ship as accommodation.