This isn't that story.

In this story, a clever volunteer at a Brunswick opportunity shop pulls a painting out of the store's "giving bin" and is taken aback by how beautiful it is.

She starts to research the artist and realises her hunch – that this painting was "a bit special" – was a sound one and after having it appraised by an auction house discovers the artwork is worth about $1800.

"I pulled it out and just looked at it and just thought, 'this is so striking, so simple', " St Vincent de Paul Society opportunity shop manager Shauna Patterson said.

"Anyone who looks says that they get the same feeling, they look at it and can just tell it is really something special."

Delivered anonymously in the weeks leading up to Christmas, the painting has its name, Spearhead Dreaming, written on the back and was signed by artist Marcia Purdie.

After immediately carrying the painting from the bin to her desk, Ms Patterson started researching the artist as all the volunteers on deck that day huddled around her to admire it.

"I put it by my desk and started to research it thinking it might be something valuable."

Ms Patterson believes Spearhead Dreaming was painted by, as well as signed by, Marcia Purdie. It uses the ochre style of painting the artist learned from extended family members such as Shirley Purdie.

Carmel Miller from the Sydney Road Vinnnies holds up 'Spearhead Dreaming'. Photo: Justin McManus

"I read up about her history, about how her painting is influenced by her family ..."

According to one artist profile, Purdie is part of a younger generation of ochre artists from the East Kimberley. She was married to Dallas Purdie, who is the son of senior Warmun artist Shirley Purdie.

While living in Warmun, Marcia Purdie built on her knowledge of the the Ngarrangkarni Dreaming stories of her Kitja Elders from Shirley Purdie and Shirley's mother, renowned artist Madigan Thomas.

"The excitement inside me was rising," Ms Patterson recalled as she learned more about Purdie.

"I just can't believe that someone would be so generous and donate such a beautiful piece of art."

She contacted an auction house that specialises in Aboriginal art that advised her this was "something she should hold on to, something that would only increase in value".

Ms Patterson then consulted St Vincent's (affectionately referred to as Vinnies) merchandise manager to help determine a price to sell the piece for. They settled on $1800.

Merchandise manager Liz Randle said the painting was priced using advice from the auction group.

"We have particular methods that we use that assist us in the appropriate pricing of unique, collectible and quirky items that come to us," she said.

"We consulted an auction group and used the internet to compare other works similar in size by that particular artist. We like to honour all our donations and when we come across one that we feel is particularly valuable, we like to ensure that on behalf of the donor we are able to get the true value of the goods."

Ms Randle has been with St Vincents for four years and in that time she said she has seen several valuable items pass through the stores.

"Surprisingly, they come through very often," she said.

"They pop up anywhere, there is no one area that gets more than others and I think that's why people shop with us very regularly."

She said often the shops would receive unique pieces of pottery, furniture, collectibles and paintings.

"We had a fob watch that was valued at $18,000 that popped up in our Horsham store a few years back," she said.

Ms Patterson said the painting is the most beautiful she has come across in her two years working at Vinnies.

She thinks the $1800 price tag in an op shop means it will be a "considered" purchase but has written an explainer that sits beside the piece in the op shop to remind customers exactly where their money goes.

"Thank you for admiring our beautiful Aboriginal art by Marcia Purdie," it reads.

"It is in excellent condition and is very unique. It was kindly donated to our store to help raise funds for our community. If you purchase me I will help support and feed many families in need in our community. Thank you for your continued support. Kind regards, Vinnies staff and volunteers, Brunswick."

David Wroth of Japingka Gallery in Fremantle, where Purdie's paintings are now on exhibition, said the Spearhead Dreaming painting relates to the rocky country where her people sourced quartz to make spearheads.

"When the people hunted there they had to bind their feet to protect themselves from the sharp, flinty ground," Mr Wroth explained.

"So the painting shows the flints that were so valuable for traditional artefact making."

Ms Patterson said there had already been some interest in the painting. "There has been a bit. I guess it's not the kind of thing that you just rush in and buy, it's more a considered purchase."

The experience, she said, reminds her of how generous Melburnians can be.

"I think was really amazing is that this beautiful donation will go to helping our community ... and we are trying to honour this beautiful donation that someone has given us to helping the community and people in need."