This Red Blue Lego Chair by Mario
Monale Minale after Gerrit Rietveld for Droog Design is for sale at Phillips de Pury. Estimate Â£20,000-25,000.
Added September 14, 2009:
It appears I made an error in this post, the same error Phillips de Pury made: The designer is not Mario Monale, but Rotterdam based Mario Minale of the Minale Maeda studio.
Here is a detail of the chair: