Offer comparison and liquidity planning for new construction, any experiences?

Initially, I inquired with a text including the floor area, number of rooms, and the building documents from the authorities. However, the providers ideally wanted floor plans (I initially thought they would create these directly with us). We then roughly drew the floor plans and specified the following special requests: ...

So an absolutely vague inquiry that a provider answers with enough buffer because they do not want to do too much work. The prices you received have extremely little informative value.

Please back to the beginning: Either buy a standard house or take the first steps with an architect. Then request offers.

So that it is comparable,

you need a basis for comparability. So absolutely identical floor plans and a tender with all positions (quantities and qualities). An architect, for example, produces this for a single-family house in about 80 pages.

No, that is not correct. We had the floor plan directly after the first time. This was the same offer basis for everyone. Points like the number of windows are of course specified equally everywhere. That is probably why all the offers are in the same price range. We only wanted to hire an architect once we know if we can even build. What is the usual procedure to inquire otherwise? We have searched the prices on the internet for a long time, and they have differed extremely in recent years and also vary greatly depending on the region and requirements. That is why I wanted to get non-binding offers directly to know what to expect. But I had actually hoped that the providers would differ more in price. As I said, we are laypeople and are just starting to get familiar with the topic. Therefore, we are grateful for all help and not just the classic "everything is wrong."

Edit: Your answers are very helpful – so please don’t misunderstand. We are currently still at the point of deciding which plot of land we can buy and which type of house we can build. Depending on how expensive it becomes, only a terraced house on the smallest plot or a detached house on a larger plot will be possible.

How is the usual procedure to inquire otherwise?

Catalog price is a reference point. But nothing more. There is no procedure except a very concrete and finely broken down inquiry - tender via an architect. To consider whether you can build or not, the well-known usual construction costs of +/- €3,000/sqm living space plus incidental costs, outdoor facilities, basement, garage, etc. are sufficient. If you live in an expensive area, you simply calculate with €3,200/sqm. If you want a good finish, a few euros more will be added on top. Unfortunately, you can't do more than that.

We only wanted to commission an architect once we know if we can even build.

The ability to build can be determined quickly. The WHAT you want can be implemented quite quickly with an architect. They have different service phases. The first two service phases are already enough. Maybe then you realize that well-planned 180 sqm are just as good but ultimately €60-80k cheaper?

I had actually hoped that the providers would differ more in price.

That is more or less the same everywhere. The E-Class, the A6, and the 5 Series BMW are comparable and have a similar price. If you want to be cheaper, it has to be the Passat. If you take a comparable good phone from the usual providers (excluding Apple here, since iPhones are overpriced), you have a similar price everywhere. And so on. Yes, the providers partly differ significantly in price. But then also in performance. Comparable material (number and quality of bricks, the same heating system, the same heating, the same toilets, the same flooring costs in the store the same price – no matter who the purchaser is) costs comparable. Craftsmen hours are also quite comparable. Standardized houses have advantages – completed plans and possibly prefabrication (in the case of prefabricated houses).

Photovoltaic + storage (10kWp + 5kWh)

Why on earth photovoltaic with storage? That makes no sense, you can save yourself the 6000 euros

Thank you. But that basically makes me optimistic that we could already afford more or that the real construction prices will be somewhat cheaper after all. For us, it should be an advantage that we bring so little expertise and therefore have few requirements. The cheap "Chinese" among the houses is completely sufficient. Then we would probably take the expensive, large plot and afterwards work out the details through an architect. But now a question that confuses me: The prefab house providers themselves have their usual contacts with architects in the region and even if I pay them separately, they presented it as the standard procedure. Do the prefab house providers only say that so that no competition is even requested?

Why on earth use photovoltaics with storage? That makes no sense; you can save yourself the 6000 euros

Photovoltaics is mandatory here and we would purchase an electric car with the house. Whether the photovoltaics and storage really need to be that large is another question. But with the current calculations from websites, I arrived at these values based on our current consumption.