The 24-by-20cm painting of a pale figure dressed in teal clothes, with teal and red hair on a crimson background, was originally sold through a website around 2001.
It somehow found itself two decades later at a donations store in South River, Ontario – 300km north of Toronto. There, an anonymous buyer paid C$5 for it.
Bowie attended art school and was an avid collector. His estate fetched tens of millions of dollars after his death in January 2016 for some 350 works from his collection – including by artists Jean-Michel Basquiat, Henry Moore and Damien Hirst.
But Bowie’s own artworks, according to Mr Cowley, rarely go on sale.
Starting with Space Oddity in 1969, Bowie scored hit after hit over more than four decades, ranging from The Jean Genie and Heroes in the 1970s to Let’s Dance and Modern Love in the 1980s to more recent hits like 2013’s wistful Where Are We Now?.
Many of these became era-defining hits around the world while successively defining what it meant to be a music legend.
Bowie died of cancer two days after the release of his 25th studio album, Blackstar, on his 69th birthday.