Billionaire Roman Abramovich and his partner Dasha Zhukova -- otherwise known as the world's "it" art collecting couple -- have turned heads with their latest art investment. The two recently purchased a collection of over 40 works by Russia's priciest living artist, Ilya Kabakov, a group of paintings and installations ranging from $30 million to $60 million.

The artworks, produced by Kabakov before he left Moscow for New York in 1987, were previously owned by U.S. collector John L. Stewart, who spent two years acquiring the massive estate. “It’s one of the largest Kabakov collections in the world,” said Emilia Kabakov, Ilya's wife and fellow artist, to Bloomberg. “It’s also the most outstanding in terms of quality and art-historical significance.”

No official price tag has been placed on the collection as a whole, though Natalia Kolodzei, executive director of the U.S.-based Kolodzei Art Foundation, told Bloomberg the Kabakov group was "priceless." (But when it comes down to it, there isn't much Abramovich, who is estimated to possess a net worth of $14.7 billion, can't afford... He's 50th on the Bloomberg Billionaire Index, after all.)

Zhukova is no slouch, either. In addition to being the co-founder and creative director at Artsy.net, the daughter of Russian oligarch Alexander Zhukov is the founder of Russia's edgy Garage Center for Contemporary Art. In 2008, she organized Ilya and Emilia Kabakov's first retrospective in Moscow, showcasing an installation titled "The Red Wagon," which is now housed in the State Hermitage Museum in St. Petersburg.