You might want to check these articles on getting started with your paid newsletter:
Paid newsletter pricing 101: How to make the most from your content117
How to launch your first paid newsletter - ConvertKit179
ConvertKit Commerce: Creating a Paid Newsletter27
With these guides, you will see the process and the payment setup that might give you some ideas on the price of your newsletter.
I hope it helps. If you're still having issues or need further assistance, you can always reach out to email@example.com.