It's not every day that you can buy a Tracey Emin or Grayson Perry for the price of a night out. But the Royal College of Art makes this possible with its ‘secret postcards’ sale – where you can bid on anonymous works by international megastars and rising talents for just £55.

You’ll never know the identity of the artist until the sale is complete, when you can flip over your trophy to see the signature on the back. Previous participants have included Grayson Perry, Damien Hirst, Tracey Emin, David Bailey, Jeremy Deller, Zaha Hadid, Maggi Hambling, Gavin Turk, Laure Prouvost and many other greats of the contemporary art scene.

This is a thrilling chance to become a collector of the biggest artists around, and an intriguing comment on how hard it is to equate value with appearance in contemporary art. This is a fantastically popular event, and people will queue overnight to be the first to spot a famous work. So stick it in your diary.