The site was offering return flights to Los Angeles and San Francisco for $788, to Houston for $848 and to Shanghai for $798.
These fares come after an announcement yesterday by Air New Zealand chief executive Christopher Luxon that domestic and international airfares would drop "substantially".
The US fares are for dates in February 2016 and the Shanghai fare is for March 2016.
Yesterday Luxon said lower fuel costs, an expanded fleet and increased competition from the likes of Jetstar would all pull down domestic and international prices.
"The combination of fuel, supply and competition will ultimately determine pressure on pricing.
"Clearly, when you fly internationally fuel becomes a bigger variable than it does in domestic New Zealand. When you fly for 12 to 14 hours, fuel can be 25 to 30 per cent of your actual cost base."
Today Qatar Airways was tipped to operate "ultra-long haul flights" between Doha and Auckland, making it the longest flight in the world.
The distance between Doha and Auckland was calculated as 14,500 km and would take 18 and a half hours according to Travelmath's flight time calculator.
Grabaseat has previously offered international fares as low as $99 one-way on some of its Tasman and Pacific Island routes, Honolulu from $299 one-way, Tokyo and Shanghai from $599 return, Los Angeles from $649 and San Francisco from $699 return.
