Cost of soil investigation

Hello everyone,
We are still very new among the home builders, as we only purchased our building plot in November and are now in the planning phase. We have not yet decided on a house type but would like to build in bungalow style. Our plot is quite large (3200sqm) and has a slope. Since we need a fully biological system, we have to submit an infiltration report.
We have decided to combine this with a soil report. However, it kind of took me by surprise.
I always assumed something like this would cost around 1k. We are at just under 3k with the offer. However, I have no idea if this is all okay. Therefore, I am looking forward to hints and comments.

Doesn't anyone have a clue about this?

Without having compared exactly now, it also feels pretty expensive to me. However, you already have alone 4 drillings and quite a bit more. But 800 net just for the report? I would simply get 2-3 more offers, or compare a bit online.

How many drillings are usually common?

I think 2 boreholes and dynamic probing? But I am not sure. Therefore, I also recommend 2-3 additional quotes.

On Bodengutachten Punkt de you can submit a request with ZIP code. We did the same and received 3-4 offers.