That’s one of the regular question. I’d try Olesya who is better oriented in these things. boxoffice.bolshoi.org has been recommended but I have no personal experience with it. Attempted going to Bolshoi once in 1993, was turned off by matreshka dolls in the lobby. I could tell you more about my Bolshoi related experiences and impressions but as it is now I think this project suffers from lack of balance and proportion between information you travellers need and my views that I try to inflict on humanity so I’ll shut up but if you think I’m just an old grouch google Bolshoi+scandals+acid to see what sort of a place you want to support by paying for these silly $400 tickets.