I don't think it is a typo. There are areas out in the sticks where nobody wants to move (because no internet, no mobile reception, no public transport, next city is 50km away, next supermarket 20km), where 100€/m² is possible.

But anything marginally close to a railway track, Autobahn or federal road or any bigger city at all is far more expensive.

I ask due to a mixture of doubt, but also curiosity: Can you point to areas with prices in the 100Euro/m² range? For a house that's suited for living, and not destruction? My grandma's house might sell for that range (~200 Euro/m²), but it has 120m², was built at or before 1900 (as a poor farmers house) and there have been no meaningful improvements since the 1970s. So, as sad as it is: Best thing one can do is scap the house and build a new one. But then it's cheaper/easier to just buy some empty land.

That town is pretty much "Arsch der Welt", though they now have 50MBit/s internet since a few years. Next city (a small Kreisstadt) has multiple super markets and is 20km away. Mobile reception in the town is okay, I think they just skipped 3G for a decade and now partially swap 2G for LTE. Public transport to/from the Gymnasium [45m bus drive] is three times a day: Going there in the morning, and returning for 13 and 18 o'clock (so pupils can get to and from school for both the regular 6 lesson days and the longer 10 lesson days). For anything else you need a car; an electric car might work, since for most interesting hacker jobs you only need a total range of maybe 150km per day (outliers in both directions apply). OTOH, even if people might seem a bit skeptical of newcomers at first, they turn out to be super friendly. After all, it's easy to know everyone by name if you're just 250 people.

Where I live (Saarland) the "Bodenrichtwert"[0] alone is usually between 80 and 120 Euro for the "affordable" areas I looked at. So little chance getting more than a ruin for 100 Euro/m².

[0] For non-Germans: The "Bodenrichtwert" is the average price per m² of "raw land", that is, excluding improvements like houses. It is updated every 2 years to include recent sales in an area.

Well, if the house should be worth anything, it won't be that cheap, yes. What you can find tons of is stuff like "Denkmalgeschützter Bauernhof Brandenburg" for really cheap, because the renovations will cost you big time. Same without Denkmalschutz (historical building protection), just not that cheap. A newly built house will cost far more than 100€/m² because building houses is expensive after all, and as you said, usually the ground is worth almost as much.

Well, then that's quite a fallacy to compare a house in the 100 Euro range to a 2000 Euro house, isn't it?

That's like buying an utterly broken, old Porsche for scrap value and then wondering how repairs like a new engine and a new $everything are costing you a fortune.