I'm going to give you two answers for the price of one, and you can
take your choice. You'll see why in a moment.
Japanese insurance magnate Yasuo Goto paid $39,921,750 for Van Gogh's
"Still Life: Vase with Fifteen Sunflowers" at auction at Christie's
London in March 1987, at the time a record-setting amount for a Van
Gogh. However, although Goto was the winning bidder, I could not find
definitive proof on the web as to whether he bought the painting as a
private party, or on behalf of his company, the Yasuda Fire and Marine
Insurance Company of Japan. I've found citations that listed both Goto
and his company as the purchaser/owner. The paiting currently resides
at Seiji Togo Yasuda Memorial Museum of Modern Art in Tokoyo.
Some links you'll find of interest...
"Van Gogh's Sunflowers: Whose Eye Do You Trust?"
Sunflowers of Vincent van Gogh ?
As you'll see from those links, there's an on-going controversy about
whether "Sunflowers" is an authentic Van Gogh or a fake. The charges
and counter-charges rage to this day...
"Expert says Van Gogh's sunflowers are fake"
"VAN GOGH'S SUNFLOWERS MIGHT LEAD TO BIGGEST FORGERY SCANDAL"
Van Gogh's "Irises" brought $53,900,000 in auction at Sotheby's in New
York City on November 11, 1987. The painting was "bought" by
Australian tycoon Alan Bond. "Bought" is in quotes because Bond could
not repay the loan Sotheby's gave him to buy the painting, and finally
the Getty Museum bought "Irises" from the auction house for an
undisclosed sum a few years later.
Further information on Mr. Bond and "Irises" can be found at...
and finally, I thought you might be interested in this link, "Top 10
Most Expensive Paintings Sold" at...
You'll note that "Irises" is in the top 10, the writer apparently
ignoring the fact that Bond actually never paid for the painting.
Number 5 is a still-life by Paul CÚzanne, "Rideau, Cruchon et
Compotier", which sold to an anonymous, private party for $60 million,
premium included, in 1999.
Search strategy: "highest amount" +painting +"Van Gogh" +sunflower