Art: How to buy a Peter Blake for pounds 30

Anyone with 30 quid and an eye for a picture can buy a work by Blake, Frank Auerbach, Edouardo Paolozzi or several hundred other artists. By Rosie Millard

A fund-raising wheeze dreamed up by the Royal College of Art, "Absolut Secret" is a public exhibition of some 1,500 postcards, some by past and present RCA students, others by the great and the good of the art world, from Frank Auerbach and Edouardo Paolozzi to David Bowie. The beauty is that each card costs only pounds 30; the catch is that all are signed on the back, and the purchaser won't know the artist's identity until after the show.

"It's a total gamble," says the artist Peter Blake, a RCA old boy. "The thing to do is to paint your card so it doesn't look like it's by you. Last year, I did a collage and no one recognised it." He estimates that such a work would go for about pounds 800 if bought from his dealer. "But it's very nice to sell your work to someone who's bought it just because they like it."

Every year, and this is the third, "Absolut Secret" (so-called because the event is suppported by Absolut Vodka) has about 100 cards left unsold, but the identities of the painters remain a mystery - artists get upset if told nobody wants to buy them.

"I was involved in a similar thing at the ICA in the Fifties," says Blake, who clearly has a sporting humour. "A hundred paintings were on the wall, a hundred lottery tickets would be drawn, and the ticket holders would have to choose, in order, which pictures they wanted. For two years running, my work was the last one hanging up. One year, the person who ended up with the picture didn't even bother taking it away. I think the only other piece in the history of that show which had less desirability was a bark painting by an aborigine."

Proceeds will go to a fund providing students with grants and hardship money. "Absolut Secret" runs from 4-8 December.

The RCA is at Kensington Gore, London SW7