Collector unknowingly bought Declaration of Independence for $4 at thrift shop and sold it for more than $7,000,000

A lucky buyer who unwittingly got his hands on the original Declaration of Independence for less than five bucks is millions of dollars richer.

Back in the late 1980s and hidden in an unassuming Pennsylvania flea market was an immaculate first printing of a vital US document that was yet to be discovered.

Fast forward a few years, and a collector just happened to stumble across the item, having picked up a 'dismal painting' because he simply liked the frame.

The unidentified buyer paid just $4 for his thrift and only discovered later that the document, one of just 25 from the original batch of Declarations printed in 1776, was found behind the painting when he went to take the frame apart.

The copy might have looked something like this (Craig F. Walker/The Boston Globe via Getty Images)

After contacting experts on the matter, he took the copy to auction in 1991, where it scored $2.2 million from the highest bidder, equivalent to around $5 million in today's money.

The historical artefact went to auction again some years later in 2000, where it had gained even more value and was flogged for $7.4 million.

David N. Redden, head of the book and manuscript department at Sotheby's in Manhattan, New York, told The New York Times it went for so much money because it was an 'unspeakably fresh copy.'

"The fact that it has been in the backing of the frame preserved it," he added, further revealing it was one of just seven copies that were unbacked, which cranks up the value.

Mr Redden described the painting that caught the buyer's eye as a 'dismal dark country scene with a signature he could not make out.'

It was then discovered the buyer has discarded the painting and even the frame that he had wanted in the first place.

"But he kept the declaration, which he had found behind the painting," he continued. "It was folded up, about the size of a business envelope. He thought it might be an early 19th-century printing and worth keeping as a curiosity."

Another original 1776 copy of the US Declaration of Independence on display in Philadelphia (ERIC BARADAT/AFP via Getty Images)

However, the unsuspecting owner of the declaration was urged to look into it further when a friend became 'quite enthusiastic' about it.

"At that point he called us," Selby Kiffer, an Americana printing specialist at Sotheby's added.

Mr Kiffer also commented on the condition of the artefact, saying it was 'just as well' it had been kept inside the painting 'less than one-tenth of an inch thick.'

"There has been absolutely no restoration, no repair. It was unframed and unbacked," he continued, with unbacked copies having increased value.

The ink was also apparently wet when it was folded.

Mr. Kiffer said: "The very first line - 'In Congress, July 4, 1776' - shows up in the bottom margin in reverse, as a faint offsetting or shadow printing, one more proof of the urgency John Dunlap, the printer, and others felt in dispersing this document."