What about existing buildings in the nearby small towns? I would also think carefully about building in a dying little town. 220€/m² is quite cheap in BW, I would also not rule out buying the land.
I understood it as the village being 5 km away from the nearest town with a school and so on, including bus connection. What is dying about that? For "not powdered" completely normal. What would rather irritate me is a direct main road on which the houses or the property might be located. Ultimately, the price-performance ratio wins.
The few km from Rahlstedt to Hamburg City is almost further. Advantage, the children can hang around outside, climb, ride bikes, without Mom and Dad always being the watchdog. Karsten