Uncovering the mysterious side of art pricing. ‘Everyone’s trying to make money’

Attorney J.D. Harriman is skeptical about some of the art market's sales techniques.

"There's very little genuine information and data on pricing," he told CNBC via video call. Prices for artworks are "rarely" displayed at galleries, he said.

"When [galleries] have a new artist, they're not going to post prices, they're going to see what their patrons are going to pay for it," said Harriman, who is a partner at Foundation Law Group.

"If a piece by an artist sold for $50K, and they keep that secret, they are able to start at a higher price, say $100K, to the next buyer interested in a piece by that artist," he told CNBC in a follow-up email.

Or, if an artwork hasn't sold, the gallery may want to discount the price — but, again, this is kept private to avoid coloring the artist's body of work, Harriman said.

Unlike with company stocks, there's no requirement to file details of the value or ownership of artworks. And, rather like real estate, insiders sometimes equate the value of an artwork with what the market will pay for it.

CNBC contacted a dozen New York City art galleries and the same number in London to request price lists for their current exhibitions. (The galleries contacted do not publish prices online.) Nine of the New York galleries responded with pricing information, while none of the London galleries revealed theirs.

In an email to CNBC, Paul Hewitt, director general of the Society of London Art Dealers, said the organization encourages its members to display prices. "Promoting public confidence in the responsible dealing of fine art is a founding objective of the Society of London Art Dealers," he said.

Galleries that don't display prices might wait for a market maker or someone with cachet to show interest in a