"Basically the demand has just been out of this world," she said. "It's the hottest toy this Christmas that most people are going to miss out on."
The innovative toy pushed the boundaries of what normal looked like, she said.
In the absence of Hatchimals Mrs van Engelen expected the Little Live Pets Dream Puppy to take out the top spot this Christmas.
The puppy moves, makes breathing sounds, can be fed and falls asleep. The toy followed a current trend in New Zealand towards nurturing play which taught children to care for something, she said.
During her last five years as a toy buyer, Lego and Nerf products had remained in the top 10 each Christmas, she said.
The companies always bettered themselves on the year before - Nerf supporting role play and Lego quality and creativity, she said.
Kiwi-born toy company Zuru had also made the top 10 again this year adding a baseball bat and launcher to its Bunch o Balloons water balloon range. Mrs van Engelen said the balloons sold well 40 to 45 weeks of the year, despite being a traditionally summer-orientated toy.
Board games were also continuing their "massive resurgence" of the last two to three years, she said.
Among the movie toys she expected the release of Star Wars Rogue One in mid-December to prompt merchandise sales but without the same huge attention as Episode 7 created at Christmas last year.
Disney movie Moana was also due for release on Boxing Day, with merchandise on sale prior.
Farmers toy buyer, Stu Gray, said he made annual trips to Hong Kong and the United States to buy toys early in the year for the following Christmas.
"You do have to make some calls quite far ahead of time," he said. "You've got to take a punt and just go with your gut sometimes."
He expected the new Shopkins range 'Happy Places' to be huge this year.
Also a range of outdoor ride-on toys, from toy company Razor, which had been out of the market for two to three years, were expected to be popular.
The success of Pokemon Go had seen a resurgence in Pokemon merchandise with a new Nintendo game released this week, he said.
Collectible Pokemon cards were also very popular. "That whole brand's just gone through the roof this year," he said.