It's not easy to get a Belarusian visa, and it's more expensive than a Schengen visa. We practically live in North Korea here.
It should be easier for Poles to get a Belarusian visa. When I was looking into getting one (about six months ago), I read that if you fly to Minsk, you don't need a visa if you stay for up to 5 days. And I read that they are thinking about expanding this, but I don't know what the situation is now.