A pair of works bought from Banksy's street stall in New York's Central Park sold for a total of £124,630 ($213,698) in a July 2 auction at Bonhams in London.
The lucky consignor paid just $60 each for the two pieces, equating to an increase of 1,780%.
The buyers were alerted to the true value of the canvases after the artist posted on his website: "Yesterday I set up a stall in the park selling 100% authentic original signed Banksy canvases. For $60 each."
Gareth Williams, head of contemporary art at Bonhams, commented prior to the sale: "The fact that his paintings were original and were being offered at a tiny fraction of their true retail value raises real questions about the perception of worth and the nature of art as commodity within the marketplace, something that the artist must be acutely aware of."
Banksy's Spy Booth is being removed from the wall it was painted on in order to be sold at auction.
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