Thank you for sharing your question with us today.
If you are talking about the Prüfung of your documents in order to get married: You will need the original document (Geburtsurkunde) no older than 6 months and have it translated by a certified translator - it is advised to talk to the Registry Office (Standesamt) before you do so, to avoid unnecessary costs and make sure they accept the translation.
As the costs vary in each Federal State, it is hard to say how much it will cost you now. I've just had a look and only found a Berlin service website displaying marriage costs at Standesamt in Berlin - from 2016.
Therefore, it might make sense to ask your responsible Standesamt about the procedure and the costs. Nevertheless, here is the German website I found: https://www.berlin.de/ba-steglitz-zehlendorf/politik-und-verwaltung/aemter/amt-fuer-buergerdienste/standesamt/artikel.87178.php
Maybe this page is also helpful: https://www.expatica.com/de/living/love/getting-married-in-germany-100926/
Feel free to reach out to us again if you have any further questions!