A cheap way to travel by train in East Europe and Russia is to buy the so called Citystar ticket. This ticket can be bought for many destinations, and in my case it was a return ticket from Bratislava to Vladivostok for 134,4 Euro and 1 month validity.
However in addition to this ticket one still needs to buy reservations for each separate train, which is especially in Russia not so cheap. The first reservation I bought was for a direct train from Bratislava to Moscow via Ukraine for 24 Euro. I bought the ticket and the first reservation at the train station in Bratislava.
It is very easy to buy a ticket in Bratislava, because everyone speaks very decent English and also some German.
I think you can also buy reservations for Russian trains in Bratislava, which I would recommend to do, because to buy a reservation in Russia is quite tricky, and I also heard that the reservation might even be cheaper when bought in Bratislava. In Moscow I paid 11442 RUB (around 280 Euro) for the reservation from Moscow to Vladivostok with one stop in Irkutsk. The Yaroslavsky Rail Terminal is the place in Moscow where you can buy tickets and reservations for the Trans-Siberian trains. Be aware that normally people at the ticket counter don’t speak any English at all.
More information about the citystar ticket can be found at:
Train schedules for all destinations in East Europe and Russia can be found at:
When searching for a train from Vienna or Bratislava to Moscow the trains showing up normally go through Belarus. Since a visa is needed to pass this country and I didn’t have enough time (another week) to get it, I went through Ukraine. This way there is also direct train to Moscow but it’s a bit trickier to find.