A bid on June 5 had the pair of medals sitting at $500, and they reportedly got as high as $900.
"Friends were contacting me concerned saying 'oh didn't know you were broke Bill'," Heke said of the advert which quickly circulated on various veteran Facebook pages.
The effort to retrieve the genuine medals in WA over the past week has left Heke and his local Howick RSA scrambling.
"I was absolutely worried. My first reaction was I had to get the ad taken down off Trade Me," Heke said.
"But then I thought if it gets taken down the path will go cold. I won't ever be able to find them again."
Heke got hold of Trade Me trust and safety leader Catherine Greene. She contacted the Australian seller who was "keen to do the right thing".
"They've been in touch with Bill and the precious medals will be returned to their rightful home very soon," Greene said. "We're absolutely thrilled."
Through the assistance of the Howick RSA, the two Vietnam medals have been purchased for $800 and are in the mail to Heke in Auckland.
However, the mystery of how Heke's genuine medals appeared for sale across the Tasman remains less easily solved.
Heke believes the medals were swapped during a brief occasion they were altered for presentation.
Heke said that happened in 2011.
The person responsible for that work has been contacted by the Herald and denied the claims, and the date given by Heke for the work.
Heke's medals have had one previous Australian owner before the current one in WA - who bought them legitimately in September 2018 through a Mowbray's auction.
A police complaint was made by Heke over his stolen medals on July 10.
In a letter provided to Heke from the NZ Defence Force, HR team leader Geoff Fox explained NZDF will only issue replacement medals to the recipient themselves or their family members.
"Except for WWII medals, all medals issued by NZDF are engraved with the recipient's details," Fox wrote.
"If they are a replacement medal for one that has been lost and not recovered, the recipient's details have added to them the letter 'R' in brackets."
The Vietnam Campaign Medal and Vietnam Medal for sale on Trade Me did not have an R engraved on them. Neither did any of the medals in Heke's possession.
However, the star-shaped Vietnam Campaign Medal in Heke's possession did not have his name and rank engraved on the back. The medal for sale on Trade Me did - indicating it was genuine.
Heke said despite remaining "furious" that somehow his medals were separated from him, he was "thrilled" they would soon be back.
"Part of my life has been returned. If I didn't get them back, a part of me would have gone with them," Heke said.
"That's the sentimental value soldiers place with these things. You don't just buy these things from a shop.
"That one with my name on it was earned with blood, sweat and tears."