Just £45 for a David Bailey? It must be the RCA's secret sale

Hundreds will queue overnight to buy postcard-size artworks that could be worth tens of thousands

Art for art's sake; money, well, that comes later. The works at a "secret" sale next month are interesting enough: a girl astride a giant rabbit; child-like paint smears; a collage of monsters; and a woman dressed as a zebra. But for at least some of the hundreds who will queue through the night for a £45 postcard there's the promise of a future profit that could run to tens of thousands of pounds.

For some of Britain's biggest names in the arts and creative world are among more than 2,500 artists who have created postcard-sized works for the annual Royal College of Art secret postcard sale on 23 March.

Among them are Paula Rego, Julian Opie, David Bailey, Christo and John Baldessari. Others include the Wallace and Gromit creator Nick Park, film director Mike Leigh and fashion designers such as Sir Paul Smith, Orla Kiely and Manolo Blahnik.

An exhibition of the postcards starts on 14 March at the RCA's Dyson Building in Battersea, London. Thousands are expected to buy a raffle ticket to see if they can be among the first 50 allowed to buy them. The identities of the artists are on the backs of the postcards, so people only discover if they have spent £45 on something by a big-name artist, or by an unknown, once money has changed hands.

Most will think it worth the gamble: a postcard painting of a man in a canoe, by Peter Doig, made £42,000 at Sotheby's in June 2007. It cost £30 seven years earlier. In the same sale, a Damien Hirst sketch of a skull, bought in 2004, sold for £15,600. A pen drawing of a figure by Tracey Emin fetched £16,000 in 2008. And earlier this month a painting of a woman by Gillian Carnegie sold for £6,000. It was bought in 1997, when the artist was a student at the RCA.

Yet, while fortunes can be made, surprisingly few of the postcards are sold on, says Wilhelmina Bunn, curator of the exhibition: "I think it's because the possibility of owning a piece by a well-known artist is so small to a lot of people that they tend to hold on to them."

In an attempt to prevent predatory art dealers hoovering up everything at the sale, the mini-artworks are sold on a "first-come, first-served" basis, with a four-per-person limit.

Now in its 20th year, the sale is expected to raise more than £100,000 for college bursaries.

Of the show's great popularity and the long overnight queue, Ms Bunn says: "By the morning, we have probably got about a thousand people waiting." She adds: "We get a few who will camp over for two or three nights."

View the postcards at rca.ac.uk/secret from 14 March