The bust sculpted as a protest by artist Sam Mahon, attracted 112 bids before being picked up by an anonymous buyer on Friday.
Mahon said he created the sculpture, and chose the medium, to protest what he considered Dr Smith's too-soft position on dairy farm pollution. He said the bust did not smell and would last forever.
The auction site listing described the sculpture as "light and hollow and highly polished".
The sculpture was on display at the COCA Gallery in Christchurch, exhibited on a steel stand.
Mahon is a Canterbury painter, printmaker and sculptor, who usually works in bronze.
He has also written three books - the latest, My Father's Shadow, was about his father Justice Peter Mahon, who headed the Royal Commission into the Erebus air disaster.
NZPA
source: newshub archive
