I will be in Uzbekistan at the end of January, - arriving on 27th January.
I have a question that maybe locals will be able to answer - is it possible to book the get the ticket for the night train Tashkent - Nukus or Tashkent - Urgench on the day of departure? I've just checked the Russian railways website (where you can see the local Uzbek trains as well) and, even for today (it's 11am in Uzbekistan now), there are tickets for the night train leaving at 6pm (for Nukus) or 8pm (for Urgench).
I would very much like to avoid having to pay an agency to buy the ticket, as they charge more than 3 times than the actual train ticket price. I think the price for Tashkent to Nukus (platzkart) is about 75-100 thousand som (I was quoted 108.000 by someone to be precise), using today's black market rate it's about up to 15 USD, but agencies charge 40USD onwards.
Thanks everyone for their input on this!