Ms Hutchison said she was told Sir Peter Jackson was also in the bidding for the medals.
"They told me there was very strong interest," she said.
"It was a real commitment for us.
"I couldn't believe it, I'm amazed I managed to be the winning bidder. We're incredibly lucky."
Auction house Noble Numismatics had the three medals displayed with an estimate of A$2500 but said they sold for A$5500 ($5610).
Ms Hutchison bid by phone, saying it went smoothly.
Her plans are to have the medals on display for the Anzac Day service at Tinui.
They will also form part of a larger Featherston Camp project Aratoi is involved in.
Mr Haglund, who funded the bid, said it was a "fantastic" result.
"That's just wonderful, it really thrills me," he said, adding the cost was within the budget he set for Aratoi.
He got behind the bid because of the Times-Age story about the medals.
"I'm a bit of an old-history buff.
"The story behind the medals, which you printed, it tickled my fancy."
He said the medals were part of Wairarapa's heritage, and should be in Wairarapa.
"It's not a big piece, like a war canoe, but every little bit counts.
"It's the taonga of Wairarapa, I didn't want to see it lost overseas."
Mr Haglund said the medals would be gifted to Aratoi when they arrived.
"It's part of being a Wairarapa person.
"The town has been good to me, it's a lovely opportunity to put something back."
Dunn's great-nephew, artist Pat White, said Ms Hutchison had called him to tell him the medals were coming home.
"It's excellent news," he said. White, who resides in Fairlie, Otago, previously told the Times-Age the medals had been the "missing link" in his research on Jack Dunn.
"I will make a point of coming up and laying eyes on them.
"I will make a special trip, that's how important they are."
He did not know how the medals had come to be in Australia, as he had thought the medals had been given to Jack's father in Masterton.
"There's all sorts of thing you don't know about the past, and that story is one of them," White said.
