Development costs for feasibility analysis of building land

ok, I did not expect that. My forecast for about 100 meters of road including water supply, sewage, electricity, gas is a maximum of 300,000 euros

What writes makes sense. That is why there are project developers with experience and corresponding liquidity. You would be eaten alive by the sharks

ok, thanks for the information so far, I was thinking of a purchase price of 50 euros per m2. The municipality offered the seller 10 euros about 10 years ago.

One more question about the planned road:

Isn't the planned road created and financed by the municipality? At least the roads that are designated as planned roads in the same development plan are now completely normal public roads.

Why should the municipality build you a road?
Try to talk to the municipality, maybe you can exchange half of the land with the municipality for a complete development?

ok, thanks for the info so far, I had thought of a purchase price of 50 euros per m2. The municipality offered the seller 10 euros about 10 years ago.

One more question about the planned road:

Isn't the planned road created and also financed by the municipality? At least the roads that are listed as planned roads in the same development plan are normal public roads today

Nope, it is basically your private development. You add it to the purchase price charged to the buyers. Professionals have to handle that.

Isn't the planned road created and also financed by the municipality?

Only if the municipality carries out the development. In the case of road construction, for example, these are the development contributions that are passed on to the adjacent property owners.
But you want to develop the building area, not the municipality. They have no money and therefore cannot do it.
Your project, your risk, but also your profit in the end – if you actually manage to pull it off and see it through to the end. The municipality will probably just say a very nice "Thank you" in the end – but nothing more.

Isn't the planned road created and also financed by the municipality?

A lot of information is missing. - Is there an ongoing land readjustment procedure? - Is the seller involved in the readjustment? - Does the area for sale also include the road area?

to sell exclusively to me and not to any developer or the municipality

- Was there "war" with the municipality?

20 years old

Looks older. When did the development plan become legally binding? Is the road area designated as a public traffic area? My version of the story (please correct): The seller owns the predominantly agriculturally used parcels 270/1 and 270/2. In the 1990s, the municipality redesigns the area with a development plan. Due to trivialities, a dispute arises between the seller and the municipality, so that the development plan is implemented except for the seller's areas. Now you want to buy the parcels and conclude a purchase contract with the seller. The municipality exercises its right of first refusal and wants to enter into the contract. Due to old wounds, the seller refuses, and you have to wait until his heirs settle the estate.