Pricing for backing up your server will depend on two things:
1) The cost of your integration (Ex. Cloudberry)
2) How much data you upload, download, and delete each month.
The cost of of the integration will vary. Please consult with the developer of the integration more info. You can visit the Integrations page here.
If you know how much data you'll be backing up on your server, you can use the B2 Cost Calculator to estimate how much your monthly B2 costs will be.