Land in sight, is house construction financially possible?

The buildings aren't actually as bad as they're made out to be here. Sure, you'll have higher heating costs of 2,000€ per year – so what, the houses are 300,000€ cheaper and already have an established plot of land.

We looked at quite a few and I have to say, if the rest of the houses were in good condition and actually that much cheaper, I would have bought an old building too ;) Here you’re more like 150,000€, max 200,000€ under the new build, and you lose the first 50,000€ again to higher incidental purchase costs. Then you renovate two shabby bathrooms, replace the original kitchen from 1970, and you don’t have that much left before we even start on the energy-efficient renovation. And we haven’t even talked about copper corrosion in water pipes or having more than two power outlets per room... An established garden is nice, but many of the existing houses were also a liability in that regard. Who could have guessed that the tree 2 meters next to the house would grow that big...

We have looked at quite a few and I have to say, if the rest of the houses were in good condition and the houses were actually that much cheaper, then I would have also afforded an old building ;) Here you are rather about 150k, at most 200k, under the new building and lose the first 50k again to higher ancillary purchase costs. Then you redo two shabby bathrooms, replace the original kitchen from 1970 and you don’t have that much left before we get to the energy renovation. And then we haven’t even talked about copper corrosion in water pipes or more than 2 sockets per room... An overgrown garden is nice, many of the existing houses were also a liability in that respect. Who could have guessed that the tree 2m next to the house would grow that big...

Higher ancillary purchase costs rather 20,000 euros (it’s only the real estate transfer tax on the difference between built-up land and empty land), but for the new building you have the house connection costs. You also have to buy the kitchen additionally for the new building. The advantage is that you can also do the renovation partly step by step. The insulation, for example, can also be done while living in the house. That works when you have saved up something again, you don’t need an expensive loan. For some, the used house could therefore become an alternative again.

Higher additional purchase costs rather 20,000 euros (it is only the real estate transfer tax on the difference between developed land and empty land),

You forget the realtor and the higher notary fees. Especially the realtor really hits hard again, and you rarely get existing properties without a realtor

You also have to buy the kitchen separately in a new build.

But that is exactly the point. In the existing property you pay for a lot of things that you then have to dismantle with effort and dispose of expensively. In the new build you only have the costs for the purchase. The calculation here compares total costs, i.e. existing property + additional purchase costs + partial renovation with land + additional purchase costs + construction + kitchen + incidental construction costs + outdoor facilities. Of course, you can reduce the costs somewhat with your own work, but that applies to both new builds and existing buildings. And many jobs you could theoretically do when you are already in. But if you need all the rooms, it’s no fun to tear them open once you’ve moved in. And then doing it bit by bit is no longer particularly attractive.

We looked at quite a few things and I have to say, if the rest of the houses were in good condition and the houses were actually that much cheaper, I would have bought an old building too ;)
Here you are rather about 150k, maximum 200k, below the new building and lose the first 50k again to higher incidental purchase costs. Then you redo two shabby bathrooms, replace the original kitchen from 1970 and don't have that much left before we even start with the energy-efficient renovation. And then we haven't even talked about copper corrosion in water pipes or more than 2 sockets per room...
A grown-in garden is nice, many of the existing houses were also a liability in this respect. Who could have guessed that the tree 2m next to the house would grow that big...

Higher incidental purchase costs more like 20,000 euros (it's only the property transfer tax on the difference between developed land and empty land), but for the new building, you have the house connection costs.
You also have to buy the kitchen additionally with the new building.
The advantage is that you can also do the renovation partly step by step. For example, the insulation can also be done while living in the house. That works when you have saved up a bit again; you don't need an expensive loan.
For some, therefore, the used house could become an alternative again.

Calculate the incidental purchase costs for a €200,000 plot of land and for a €500,000 house.

Existing properties are not a piggy bank, that's true. However, they don't have to and can't be, because with existing properties you usually pay for a fully finished house. Whereas with new builds, often, naively or intentionally to make the numbers look better, only the land, turnkey house, and maybe a small buffer for the kitchen are planned.

We could have bought an existing property in 2019. Similar size of land and house, everything fully finished. It was too expensive for us. Even without the 2021 price adjustment, we have come out significantly more expensive with the new build now. And that doesn’t even include all the work that is already in here and still to come... and especially the nerves when the wife thinks it's not going fast enough again or the know-it-alls come by for the "acceptance" :D
Whoever I ask here... once you get a bit more familiar and then talk: most people, especially those with children, are slowly fed up with the hassle about a year after moving in...
So another round of scraping together money or pestering the family to get a garden landscaper (from Poland or Ukraine) to set the fence, the L-shaped stones, etc., because people totally overestimate themselves.

In short:
An existing property is (significantly) cheaper than a new build if you don’t just consider the new build as a house on gravel, but including finished landscaping, interior fittings, garden, etc.
Otherwise, you are comparing a used BMW 5 Series with full equipment to a new car in the accountant version on 16" steel rims, without navigation and with fabric seats.

You forget the real estate agent and the higher notary fees. Especially the agent hits you hard again and you rarely find existing properties without an agent.

But that is exactly the point. With an existing property, you pay for a lot that you later have to dismantle and dispose of expensively. With a new build, you only have the costs for the purchase.
The calculation here compares full costs, i.e. existing property + additional purchase costs + partial renovation with land + additional purchase costs + construction + kitchen + incidental construction costs + outdoor facilities. Of course, you can reduce costs a bit with your own work, but that applies to both new and old buildings. And many tasks could theoretically be done once you are living there. But if you need all the rooms, it’s no fun to tear them up once you have moved in. And then doing it gradually is no longer that attractive.

Whoever sells with an agent has to bear the broker costs themselves, which are then deducted in the negotiations. That should be possible again at the moment.
And of course you do not pay for a 50-year-old kitchen.
That was surely different in recent years when almost every price was paid. Now it is different again, and there will be price negotiations where such things are taken into account.
Higher notary costs are negligible; they probably just reach the four-figure range.

That’s why I wrote that, for example, insulation can be added later. Bathrooms can be renovated too, if you have two of them. Pipes and electrical work are better done beforehand.

I think you just can’t generalize this anymore now. A year ago you were right, meanwhile it is turning back a bit.