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Van Gogh's Sunflowers (1889) purchased by Japanese Insurance Company in 1987.
Just judging from the 'then and now images' of a Christie's auction I would guess that the original Christie's auction setting would have been quite chaotic and not quite as gentile. In 1810 Christie's buyers would most likely have been art dealers themselves, looking to buy wholesale with significant retail mark up for their clients. This has changed significantly in the evolution of Christie's because the new buyer tends to be the private collectors themselves and tends to be new money rather than establishment.
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Another major changed that has occurred is the social status of the auction. In 1810 Christie's auction floor looks frantic as the pushy buyers mirror cattle being herded. Today auctions have morphed into entertaining events where people go to be seen. Also, in the early stages of the art market selling a painting was seen with stigma. It was likely assumed that the selling of a painting only resulted in a need for quick cash. Today, many sellers plan to donate the earnings of a sale to philanthropic efforts. One example of this is when David Rockefeller sold his Mark Rothko painting in 2007 $72 million US dollars at a Sotheby's contemporary art auction. Mr. Rockefeller had owned the painting for 47 years and stated that he would put the paintings proceeds towards charity. Mr. Rockefeller also had a private box to watch the auction from which shows how entertaining an auction could be. The Christie's live auction has truly evolved since it's inception and has ultimately become quite an integral part of not only the art market but the global economy.
David Rockefellar's Mark Rothko painting White Center (1957)
Purchased by Rockefeller for $8,500 or $59,000 in today's dollars and sold for $72 million US dollars in 2007.