Is the construction project feasible and realistic?

Children are not planned at first.

Just for orientation: We currently have several offers from prefab house manufacturers, and none of them is below 1,800 euros per square meter of living space (each for the second highest development stage "almost turnkey"). The advisor of the provider we will most likely go with in the end told us that prices have increased significantly in the last 2 years. In the construction industry, prices of 20 euros per hour and up are currently being asked, and this is immediately reflected there.

1,300 euros might still work as a shell construction if you are skilled at craftsmanship yourselves and/or your circle of friends mainly consists of painters, electricians, etc.

Just for orientation: We currently have several offers from prefabricated house manufacturers, and none of them are below 1,800 euros per square meter of living space (each at the second-highest expansion level "almost turnkey"). The advisor of the provider, which will most likely be the one in the end, told us that prices have risen sharply again in the last 2 years. In the construction industry, rates of 20 euros per hour and up are currently being charged, and this is immediately reflected there.

1,300 euros might still work as a shell construction, if you are handy yourselves and/or your circle of friends mostly consists of painters, electricians, etc.