V.P.
I have a linen sheet from my childhood -- somehow I ended up with it. I think it was wrapped around a dress or something once when I moved. It's at least 40 years old and hard used for 20 years. It is very soft and nicer than anything I've ever purchased. I don't know that you have to go to Belarus for nice linen sheets - it'll be impossible to return them if you don't like them. But there are a lot of companies in the US that sell 100% linen sheets.
http://www.linoto.com/Default.asp
ETA: Keep looking on line for 100% linen sheets -- I saw quite a few sets yesterday when I was looking for around the $240 price