Financial requirements for building a prefabricated house

Just have an offer made for the dream house, then you have a large item relatively firmly fixed in the calculation.

I actually plan to do that too, I just don't know exactly if it makes sense already - a year in advance. That is definitely the biggest unknown for me.

You will not get by with the €135,000 for the house. Even if you add the €33,000 for the equipment, of which about €10,000 - €15,000 will go towards the foundation slab. With that, you might get to the point where the bare house is standing. But then you still have no floor and wall coverings installed. If you include the €15,000 for the outdoor facilities in the house costs, it might just work out.

Besides the construction costs, the financing side is also interesting to look at. You get an interest-free loan from the client (good), then the big chunk of loan and KFW153 at 1.9-2.0%, and then you attach the 124 block to that? Do you already know if it pays off in the end? I would also have other offers calculated without the 124 just to be safe. The program is often already uninteresting with some equity and subordinated/unsecured client loans.

. The program is often already uninteresting with some equity and subordinated/unsecured AG loans.

This still needs to be clarified - unfortunately, the responsible employee for internal loans is currently sick. Of course, I will still obtain offers from other financial service providers.

Shared my experiences: we have been dealing with the topic of house construction for 4 years, and in 2 weeks the excavators will finally roll up at our place... At first we thought everything would be done with €250,000 (excluding land). From prefabricated house providers to construction companies (all from one source) to an architect-designed house, we went through numerous invoices, offers, and considerations. As a result, our estimated budget rose to €300,000. After further rounds of offers, it then went up to €325,000... With that, we entered the race concretely, to our architect. Here there was still something that added to it and we reached €350,000, which we then declared as our maximum. Until further additional costs appeared and we are now at over €400,000 with all our wishes and incidental costs. We have a structurally not simple floor plan and no uncomplicated statics but our dream house. For Kfw 70, controlled ventilation and heat pump we then gave up for cost reasons.

But the time was worth it. Because over 1/3 of the costs are paid or commissioned as of today and we are slightly below the estimated costs.

I actually plan to do that too, I just don't know exactly if it makes sense now - a year in advance. That is definitely the biggest unknown for me.

Exactly, and if you already know approximately what it will cost, that helps you.
Just let the sellers do the calculations.