If you are looking for land around Warszawa, firstly take into consideration the new ring road that will be built. I would suggest the area around Podkowa Lesna, This area will be a competitor to Konstancin over the next 10 years. The infrastructure is good and it is close to the roads leading to Wroclaw, krakow and Poznan. But you do know that as a private person you have to get permission to buy- unless you buy through a Polish passport holder or registered company in Poland
Polish People also have a real obsession about forests and having a plot with trees on it.