OK, in a nutshell, what is the best way to buy train tickets for trips outside of Russia not through an agent?
I am buying my internal tickets for the Russian legs of the Trans-siberian through rzd.ru but they don't allow purchase for trains going outside of Russia, so how do I do this?
Can I buy tickets at Irkutsk station for Irkutsk-Ulanbator and then can I buy a ticket at Ulan-Bator onto Beijing? Or are there agents online for these legs that just charge a small amount?

