It will be the best thing that can happen to Germany if Poles are buying the deserted real estate in the east. Since eastern Germany was left by its working populace years ago, there are only old or unwilling people left. Many houses and flats are empty. It is okay with me if there comes live and money into the east. Poles are catholic, civilized, educated and they arrange themselves. Just come in and invade Leipzig, Dresden, Frankfurt/Oder, Görlitz or whatever but do not forget to pay your taxes...
;-)
BTW - those prices are only realistic in the far east of Germany. In the western part you have to pay for a good family home around 200 - 250.000,- Euros on the countryside and up to 1.000.000,- Euros in bigger towns due to expensive ground. That are no (!) manor houses with pools.
P.S. As an architekt I know what I am talking about.