Amazon S3 Deep Archive and rclone for < 4-5TB. Backblaze in a Windows VM or container for 5TB+.

How much is this a month? Opendrive.com is 100 USD a year for 10 TB

You can look at their pricing (it depends on region).

With my usage I'm paying about $25 annually using S3. But if I ever need to full restore I'll be paying around $100 in data transfer fees.

Do you have a write up on how to do these?

No, I sat down for an evening and figured out rclone from their docs: https://rclone.org/docs/