London, England (CNN) -- She died almost fifty years ago but pop culture's fascination with tragic Hollywood star Marilyn Monroe continues unabated.
Performers from Madonna to Lady Gaga to Lindsay Lohan have emulated Monroe's signature pin-up style, while countless books have been written about her since she died in 1962 from a barbiturate overdose, aged just 36.
Not only do people want to know about her and look like her; collectors around the world will pay top dollar to possess something once owned by the iconic, flawed actress.
Auctions of Monroe memorabilia are known to cause mayhem in the sales rooms. In 1999, a sale of her possessions at Christie's in New York, including the famed sheath dress she wore to serenade President John F. Kennedy on his birthday in 1962, induced feverish bidding. The dress eventually went under the hammer for $1.2 million.
There is one collector who claims to own the lion's share of Monroe memorabilia -- including some of her most famous dresses, such as the plunging red sequin dress from 1953 film "Gentlemen Prefer Blondes" and a skimpy black flapper number from 1959 film "Some Like it Hot."
Investment banker and collector David Gainsborough Roberts, remembers the first Marilyn item he bought, in London in 1991: "It was a swimming costume from 'There's No Business Like Show Business.' There was a bidding frenzy; nothing of Marilyn's had come up for some time."
Roberts eventually got the costume for £15,000 (approximately $24,000) and his collection developed from there. He bought the red sequin dress from "Gentlemen Prefer Blondes" in 1991 for £18,000 ($29,000) but thinks it would now be worth many times that today.
Precious costumes and personal effects from Roberts' collection are going on display at the American Museum in the UK in Bath Saturday for an exhibition entitled "Marilyn -- Hollywood Icon."
Laura Beresford, curator of the exhibition, thinks audiences will be surprised to see that behind Monroe's glamorous image was a woman with simple tastes.
"For a girl who is famous for singing about and extolling the virtues of diamonds, she herself was not material in any way," said Beresford.
Her own possessions may now be coveted by eager collectors happy to pay thousands -- if not millions -- of dollars for them, but Marilyn herself was generous to a fault, said Roberts, and frequently gave her possessions away to friends.
Her generous nature and bad financial sense meant that the actress, whose estate now nets millions a year, died $400,000 in debt.
Of her personal possessions, Beresford said: "They're terribly mundane, bashed about, and not particularly Antique's Digest at all. She kept things with her because they had sentimental association."
One of the most poignant pieces is a little brass dancer, which Marilyn owned as a child when she was living in an orphanage. "Apparently, she used to hold this brass figure and tell people that this is what she was going to be, she was going to be this star," said Beresford.
So why does Marilyn Monroe, born Norma Jeane Baker in 1926, continue to fascinate? According to Roberts, it is because she appeared to have everything and yet have nothing at all.
"She died in a little bungalow, in a cluttered room, bombed out of her mind on pills and unhappiness and I think people identify with that," he said.
Biographer Keith Badman, author of recent book "The Final Years of Marilyn Monroe: The Shocking True Story," meanwhile says that her appeal lies in her closely managed image.
"Her image is forever locked in that beauty, we will never find a picture of her looking old or past her prime. She was an exceptionally beautiful woman and she died very young," he said.
And the silkscreen paintings of Andy Warhol, thinks Beresford, have elevated Marilyn to a fine art icon as well. "She's become almost a decorative motif, which can be applied to all sorts of art -- and we instantly recognize her," she said.
Our appetite for Marilyn, it seems, is insatiable. Roberts' collection may be extensive, but the jewel in the crown for him would be the billowing white dress worn by Monroe in 1955 film "The Seven Year Itch."
Owned by film star Debbie Reynolds, Roberts said that it is going up for sale in Las Vegas this summer. "Every time I talk to Debbie, she mentions millions," said Roberts.
"If the 'Happy Birthday Mr. President' dress fetched $1.2 million, then they've got to put over a million on this one," he said. "I wish I could afford to buy it."