Planning prefab house, first appointments are scheduled

...is completely "normal" in the commuter belt. If you haven't just forgotten to build a street into the town, you won't get under €500 before a 30km radius. But not from private sellers and only with a child bonus.

Well, I often read here about "your" prices and therefore your worries down there in the south or BW or BY. In this case, the OP made me curious because I read between the lines that he hasn't really dealt with plots and their offers yet, and I read the flexibility as very limited. So I took a look at Immonet. Here in Hamburg, the madness is also slowly starting. Slowly... In addition, there is the minimum size of 650sqm for an independent plot. Even though the salaries are higher, they are by no means twice as high as ours – but we have built for a fraction.

I hope we don’t unsettle too much. Anyway, the longer it takes to find a plot, the more equity grows.

It is what it is! But I would also get choked up over it, especially since everything gets more expensive every year.

The prices are crazy. They teach fear when building new and bring joy when selling the old property. Southern English conditions until the bubble bursts.

for that, one earns an amount X more in these regions. If one does it smartly^^

you earn an amount X more in these regions for it. If you do it smart^^

...as Yvonne already wrote - but not double.

The prices are crazy. It teaches fear when building new and brings joy when selling the old property. South English conditions until the bubble bursts.

...slower price increase, stagnating or eventually declining - yes. In the short term, I don’t see that though, and certainly not a bubble. Except for a global total disaster, there is currently no indication of a bubble.

To get back on topic... waiting for it to become cheaper will probably not work. But you should still only buy/build when it is financially healthy. For the OP, that currently means reconsidering the demands (building smaller yourself will be difficult with the budget) or moving further away from Benztown.
If those are no options, the Swabian can only do one thing.

When I had already read 20km from Stuttgart, I realized that the budget was not enough. Just because your acquaintances built on 300sqm, it doesn't mean you will get a 300sqm plot. Every sqm hurts at these land prices. Above all, I don't know how you come up with "from 200€" per sqm? From a private seller, you will pay 3-4 times that, and from the municipality, you won't get anything due to the high number of competitors.

Off-topic: Nowadays, developers come up with strange ideas. A friend of mine is currently looking for a property in the Ruhr area and said that some developers no longer divide the parcels to save costs. In other words, you build a semi-detached house, townhouse, terraced house, etc., but in terms of land, ground, and rights, you are treated like a condominium buyer because there is no individual plot. That means all "co-owners" have to be asked (and agree) if you want to put up a swing, garden shed, etc., in your piece of garden.

Totally crazy.

Nowadays, property developers come up with strange ideas

Nowadays? The Deutsche Reihenhaus has been doing that since its founding. That was around 1900.