When the organisers of an autism charity in the West Country decided to hold a fundraising auction to modernise two ageing buildings, they hoped to persuade a few local artists to donate work.

But to the astonishment of managers at Spectrum, which provides care services for those with autistic disorders, they began receiving artistic contributions from some of Britain's most eminent artists, with Hollywood celebrities coming on board after word-of-mouth news spread to Los Angeles.

Damien Hirst drew a doodle of a shark on an out-of-print catalogue while Norman Foster contributed architectural plans and the Royal Academician Norman Ackroyd offered an evocative etching entitled Windemere.

Stella Vine, who rose to fame after being championed by Charles Saatchi, was so touched that she spent a week learning about the service in Cornwall before producing two paintings for the cause while the architect Sir Nicholas Grimshaw asked if he could donate sketches of the Eden Project.

The actors David Arquette, Courteney Cox and Cher made their own donations after learning about the auction from Matthew Stokes, an LA-based architect and interior designer. Others who contributed include the British pop artist Gerald Laing, Chris Levine, who has created a hologram of the Queen, and the street artists, Eine and D*Face. Signed books have also been given by authors Nick Hornby, whose son suffers from autism, and Philip Pullman, among others.

The result is a vast collection of 108 pieces of art, as well as signed books and photographs in an auction of unexpected scale after an appeal that was initiated by the artists themselves.

The event, which was set to take place over one evening, will now be launched on 3 November at the Headland Hotel in Newquay, and continue as an online auction thereafter.

Sarah Miller, a manager at Spectrum, said the auction was part of an effort to raise £500,000 for improvements to a former rectory in St Erme, Cornwall, which was converted into a residential home by the pioneering parents of children suffering from autism and Asperger's syndrome 24 years ago.

She began speaking to local artists but others from further afield soon began contacting he. "We pitched it on a Cornish level, but after we talked to the artist Paul McGowan, news began to spread and I had artists phoning me saying 'I know someone who's involved. Can you take a picture from me too?'

"It wasn't a very public campaign but people came to us. Many artists wanted to be associated with the charity because they identified with the cause. Matthew Stokes got to hear about it and because he's an architect in LA at the moment, he spread the word in Hollywood."