Cost estimation of a simple utility basement

We plan to build an extension onto an existing building and to partially cellar this extension. The footprint of the extension is 45 sqm, about 35 of which should be cellar space. Excavation would not need to be done directly at the outer wall of the existing building, but about 2 m away from it. We hope this will make the underpinning easier/not too costly. We plan a simple utility cellar as storage and workshop. [Weiße Wanne], completely underground, unheated, uninsulated, with cellar access from inside and outside, 1 cellar window at the cellar entrance on the outside. No interior plastering needed, no water connection needed, only electricity. Screed on the floor is sufficient. It does not need to be nice, just functional. Approximately what costs should we expect (excluding earthworks)? Unfortunately, we are completely clueless.

We are planning to build an extension onto an existing building and to partially basement this extension. The footprint of the extension is 45 sqm, about 35 of which should be basemented.

Segmental approaches are no good; consider the future building as a whole. And start with the most thorough investigation of the existing structure.

Okay, thank you very much for the answer. I have also read that a partial basement is not really cheaper than a full basement. However, I also read everywhere that you should preferably not dig directly next to the existing building? But well, as a layperson, that's probably really impossible to judge. I have no idea what technical aspects need to be considered when building a basement. That's what a company does anyway. Has anyone here recently built a basement and would like to share their experiences? Even if it's not a comparable basement. Just out of interest and for the exchange.

Without a plan, roughly 70k. The [Weisse Wanne] makes it very expensive.

Is the existing house basemented?

I have also read that a partial basement is not really cheaper than a full basement.

Yes, see the second 11ant basement rule in "Partial basement: The solution between yes and no?".

However, I also read everywhere that you should avoid digging directly next to the existing building if possible? But well, as a layman, you probably really can't judge that. I have no idea what you have to consider technically when building a basement. That's what a company does anyway.

The excavator digs and scoops, the architect plans. Your idea that a two-meter safety distance would impress the ground is very naive. It would only bring you the disadvantage here of not having connected the entire building in the basement and needing a second basement staircase.

I had also expected 70k. The existing building is partially basemented, but only in the front area. A small basement room of maybe 12sqm (the house is from 1900). There is also no staircase down, only a hatch in the floor, accessible from the current kitchen, with a chicken ladder. We would not use this old basement at all. We would build an extension and basement in the rear area, about 8 m away from the current basement. We do not have a soil report. Therefore, I initially assumed the worst (=most expensive) and planned for a white tank. Maybe we can do without it. It is not supposed to be a residential basement.