Construction costs are currently skyrocketing

Honestly, this 5000 euro limit surprises me because it doesn't seem particularly high to me personally. Our household income is pretty much exactly at this level, and I rather have the impression that we are rather in the middle range in our environment.

5000€ is already very generous. The problem is that with rapidly rising inflation it is worth less and less, and for example here in the house building forum you almost only deal with people who have a significantly higher income than average. Ask in the panel building complex who has a household income of over 3000€. There you might have that at most gross. They then say they don't know anyone who has a household income of 5000€.
Edit: According to Statista, from a net household income of 4500 and more, you belong to the top 10% income earners in Germany in 2022.

Neighbor today mentioned a few prices of offers he accepted: 80sqm attic roof battens and osb (I think) installed by the roofer: 1000€ 120sqm wallpapering and painting white on q2 - 16000€ Flooring installation - 8000€ (it's probably laminate, I don't know more) 100m fence double rod 180cm high - 12000€ All net

Neighbor named a few prices today from offers he accepted: 80sqm attic battens and OSB (I think) installed by the roofer: €1000 120sqm wallpaper and painting white on Q2 - €16000 Flooring installation - €8000 (it's probably laminate, I don't know more) 100m fence double rod 180cm high - €12000 All net prices

Roofer cheap, painter expensive, fence price also okay

120sqm wallpaper and painting white on q2 - 16,000€

120 m2 wall surface for 16,000€??? Something must have gotten mixed up…

120sqm floor area, height of the walls is unfortunately unknown to me
Maybe I should have mentioned that, sorry

100m double rod fence 180cm high - 12000€

I just had it done for €55/m gross in much smaller quantities. 8/6/8 quality. Crazy what people are willing to pay.