Doesn't it? [1][2] suggest that Germany paid $25bn for fossil fuels to Russia in 2021, where a large portion of this must be gas. The cost of building Nord Stream 2 was less than €10bn and some of that was probably covered by Germans. So, it might cost something similar to one year supply. Keep in mind that gas contacts are often long-term.
Also, you assume the pipelines are irreparable, but we don't know that.