Imitation of life: He almost duped Andy Warhol's estate. Now Charles Lutz is targeting the auctioneers

In the wake of Damien Hirst's ground-breaking Sotheby's sale this week, which fetched a jaw-dropping £111.5m, what could be more timely than an exhibition that explores the notions of authenticity and value in the modern art market – and fetishises those involved? The Brooklyn-based artist Charles Lutz, a former assistant of the American king of kitsch Jeff Koons, was so intrigued by the cult of the modern artist that he meticulously copied Andy Warhol's 1954 Self Portrait with silver hair 12 times, in four different colour versions. He then submitted his forgeries to the Andy Warhol Art Authentication Board. There, they were officially stamped with "Denied" and returned to the artist, who promptly put the tampered-with works on show.

"The authentication board was right down the street from Jeff Koons's studio, where I was painting the big lobster that runs across Koons' billboard-sized Triple Elvis painting of three female nudes," says Lutz, now 26. "I pretended to be a delivery boy. It's a three-month process because they only review work a few times a year."

Now his Denial and Acceptance Series (2007) is being exhibited for the first time in the UK, along with his new works, including the Sold series of round paintings. They feature Sotheby's auctioneer and world head of contemporary art Tobias Meyer, in enamel and 23-carat gold on canvas over panel, based on the designs of 19th-century gilded French porcelain.

How did it all begin? Lutz was initially inspired to copy the paintings after a Warhol self-portrait, owned by film producer Joe Simon and valued at $1.4m, was deemed a fake by the Board. "They stamped his painting on the reverse in red and black ink that bled through to the portrait. Now they stamp it in a lighter blue-green ink on the wrap-around of the canvas, where it's stapled," says Lutz. In an instant the painting became worthless. "They don't have to answer to anybody but it is in their own interests to keep genuine Warhols low," says Lutz. "Its authenticity should have been questioned more – but the uproar fizzled out quickly."

The portrait had been deemed authentic by the late executor of Warhol's estate Fred Hughes, before Simon bought it. The board is secretive about how it determines what is and what isn't a Warhol. Lutz went on to copy Warhol's Marilyn Monroe canvas as well as the artist's oxidation portrait of Jean-Michel Basquiat – both now stamped with "Denied" and appearing in the show.

"They serve as a commentary on the easily reproducible aspect of Warhol's work, as well as how we apply value to a work of art," he says.

Lutz is the highlight of Project One: Icons, a show that celebrates iconic images from pop to urban art at 108 Fine Art in Harrogate, North Yorkshire, and includes paintings, sculpture, and prints by Peter Blake and Julian Opie, as well as Sex Pistols artwork by Jamie Reid and works by Banksy and Blek Le Rat. It is the first time that he has exhibited outside the US.

Born in Pittsburgh, Pennsylvania in 1982, Lutz attended the Pratt Institute in New York, where he studied painting before becoming Koons's photo-realist painter from 2005-2007. Lutz found the experience with Koons invaluable. But working for such a high-maintenance artist, one famous for Puppy – a 43ft tall topiary sculpture of a west Highland white terrier – and the sexually explicit Made In Heaven series featuring his Italian porn star wife, La Cicciolina (Ilona Staller), had its challenges.

"Jeff presented himself as a family man – not as flamboyant as you would expect," says Lutz. "The Denied series was my way of replicating something that Jeff was doing but on a more basic level. Jeff might reference a Warhol Elvis painting – but rather than take it and try to over-intellectualise it, I take it for what it is, and the problems that arise in creating something that already exists."

Having pulled off his Warhol coup, Lutz turned his attention to a series of circular paintings, Sold, which critique the art market, and in particular contemporary art at auction. Hawk (Tobias Meyer) – depicting the esteemed auctioneer alongside a gilded hawk –spares no expense in its attempt to mirror "the indulgent nature of art collecting" and the "flock-like atmosphere of auctions".

"Like Hirst, I am acknowledging the importance of the secondary market, especially auctions. It is interesting that it has taken so long for artists to take new work straight to auctions."

Two Birds – another round piece – set against a lime-green background shows Meyer's face, alongside two chubby birds. Christ – also in the Sold series – is clearly a play on the word Christie's, whose shiny logo is plastered on the wall behind another of his auction paintings. "There is conflict in having a charismatic auctioneer. Meyer has the power to create a demand for something and to influence prices in contemporary art," says Lutz. "These paintings reflect the character of the market. We are in a time of financial uncertainty yet the rich are spending even more now in the US. The paintings are not preaching to a mass but to the powers that be."

Lutz is also exhibiting a towering sculpture – Stacked – in the show. Made up of three stacked boxes, hand-tacked in leather vinyl in Louis Vuitton-style print and silk screen printed in enamel paint with Brillo, Heinz and Kellogg's logos, it refers to Warhol's sculptures of the Sixties such as Brillo Box and Heinz Box. "But I raise the stakes of everyday objects from the level of high art, to the level of luxury." Lutz also sells his own Brillo Box sculptures in a limited-edition run of 50 for $4,000 each online. The round paintings are all one-offs, with Hawk (Tobias Meyer) selling in the exhibition at £7,000. The Warhol copies start from £1,500 for a red Self-Portrait.

Project One: Icons, 108 Fine Art, Harrogate (01423 884 400; www.redhouseoriginals.com); 20 September to 11 October