Modern coins are worth face value. According to xe.com, one New Zealand dollar is worth about 75 US cents. If it were made of gold, that would be a different story. But it's made of aluminum-bronze, so face value is all you can claim.
Collectors will pay a tad more than face value for coins that are in really nice condition, like the one in our picture. Figure $2 to $3 US dollars for an uncirculated specimen.