The Northampton Town Supporters Trust has been auctioning off club memorabilia to try to raise £100,000.
The winding-up petition brought by HM Revenue & Customs has been adjourned until 30 November.
The online auction has so far raised £40,000 towards costs.
Akinfenwa, known as The Beast and now an AFC Wimbledon striker, scored the hat-trick against Accrington Stanley in 2012.
Ben Trasler, a volunteer from the trust, said the winning bidder told him his company had gone into liquidation the day before the auction ended so was unable to pay.
"Having done a bit of investigative work, it appears an unlikely story," he said.
"He didn't strike me as being consistent with someone who has over £7,500 available."
Mr Trasler said he was "sceptical" that the buyer would pay as the auction price rose through thousands of pounds.
"It's disappointing because there's a lot we could do with that money," he said. "We're deciding whether to relist the item on eBay."
The League Two club has been taken to court over £166,000 of unpaid taxes. Players and staff were not paid in October.
The club also owes Northampton Borough Council £10.25m, which was loaned to redevelop Sixfields Stadium.
Former Oxford United chairman Kelvin Thomas is interested in buying the club from current owner David Cardoza, but Mr Cardoza is also in talks with former Swindon Town chairman Jed McCrory.
A football fans' trust trying to save its club from a winding-up petition is down £7,500 after the successful bidder for Adebayo Akinfenwa's hat-trick shirt said he could not pay.