Apparently, it costs $2M to rent the place out for private event.
"...Superstar Lady Gaga even performed for the wedding party in a performance which is believed to have cost a further £1.6 million...."
https://www.thesun.co.uk/living/3937180/russian-tycoon-daughters-stunning-wedding-flowers-lady-gaga
One more thing: it was, in fact, an Armenian wedding. It just ignorant media calls everyone Russian from that neck of the woods.
Bride - Lolita Osmanova, groom - Gaspar Avdolian.