Thanks for reaching out to Microsoft Q&A.
Based upon Event hub tier, your cost will vary. You can use pricing calculator and check the cost as per the location where you're planning to deploy it.
Please check below link -
If you scroll down on above link, you will see option to select location and based upon that you will be able to see details for each type of event hub . Reference screenshot
Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.