Went there in 2000, it was well worth it, however we were lucky in such a way that it was part of a summer school between my university and Moscow Aviation Technology Institute (Star City was also impressive).
So never paid a thing for the visit, and the guide was this very old retired pilot who knew freaking everything about the aircraft on display and the museum.
Once again I recommend it, it was amazing!
ps: I struggled indeed to get a visa, the russian consulate kept sending me back my forms saying that something was missing or that I needed to pay extra cash for whatever reason, so I got the advice to write a nice letter with my file, saying "thank you for taking care of my file" etc, etc....and it worked fine!
No matter what anybody tells you, words and ideas can change the world.