One company in Minsk takes orders and sells saunas made from
logs. The minimum price of a simple sauna is $250 USD for 1 cubic metre
at company’s site. There are variations if you choose certain type of
wood; ask to build the building on site, as well as other extra. How
many cubic metres in a decent size building I don’t know.

I think they are affordable. Company’s ad. In the end of the video some maybe houses rather than saunas.