A thrift store shopper joked she’d found a famous artist’s work for $4. It turned out she really had

(CNN) : When an antiques enthusiast purchased a painting that appeared to bear the signature of N.C. Wyeth at a thrift store in 2017, she joked that the $4 item might actually be a real work by the prolific Maine artist and patriarch of the Wyeth family of painters. Her joke was no laughing matter, and the painting is now estimated to fetch as much as $250,000 at auction in September.

According to specialists at Bonhams Skinner auction house, the seller unknowingly purchased the work at a Savers thrift store in Manchester, New Hampshire, while searching for frames to reuse. The Wyeth painting had been stashed against a wall along with mostly damaged posters and prints, according to the auction house.

The woman took the piece home but could not find any information about the work with a quick internet search. After hanging the painting in her bedroom for several years, she eventually stored it in a closet in her home.

Bonhams Skinner auction house expects the painting to fetch between $150,000 and $250,000 at September’s auction.Bonhams Skinner

She rediscovered the painting this past May while cleaning, and this time posted images of the work on a Facebook page titled “Things Found in Walls,” which is dedicated to “stories of things you have found in walls, dug up in your backyard, or in that abandoned house across the street from your grandma’s,” according to the group’s description.

Comments on the post led her to contact Lauren Lewis, a former curator who worked with paintings by three generations of the Wyeths: N.C. Wyeth, his son Andrew Wyeth and his grandson Jamie Wyeth. After seeing the piece in person, Lewis was “99% certain it was authentic,” she told The Boston Globe.

“While it certainly had some small scratches and it could use a surface clean, it was in remarkable condition considering none of us had any idea of its journey over the last 80 years,” Lewis told the Globe.

Wyeth often produced cover art for publishers of periodicals and novels. The painting up for sale in September is one of four he completed for a 1939 edition of Helen Hunt Jackson’s book “Ramona,” originally published in 1884. In it, Wyeth painted the young title character facing her elderly foster mother, while a statue of a religious figure looms between the women.

Only one other has been recovered, according to Bonhams Skinner. Auction house specialists believe the publishing company Little, Brown and Company may have passed the work along to an editor or to the author’s estate.

The auction record for any member of the Wyeth family was set last year during the sale of Microsoft co-founder Paul Allen’s collection at Christie’s New York, where Andrew Wyeth’s 1980 painting “Day Dream” sold for over $23.2 million, more than seven times the high estimate of $3 million.