Encryption doesn't cost extra, it doesn't look like, but since my Borg clients already encrypt before they send data to the Borg server ( tennessine) there's no need for B2 to encrypt things. Also, I do not have Backblaze encrypting the files I upload. I also set the LifeCycle rules to only keep the latest version of any uploaded file, since Borg keeps track of these files. I made my bucket private, so only I (or Backblaze) has accesss to the bucket.

These instructions have you create your first B2 bucket, you can do that now, or I show you how to do it later from the command line. If you haven't created a Backblaze B2 account yet, follow the Backblaze B2 Quick Start Guide. If you have a cloud storage provider that is even cheaper than this, with better terms, please leave a comment below! There is also no minimum storage duration, so you can delete files as soon as you upload them (this is important since Borg could possibly delete files immediately after a prune and compact step). They also don't have complicated tiers of storage, every stored file is hot, it can be downloaded as soon as it's uploaded, and there is no limit to how much you can store or retrieve. Downloads are $0.01 per GB (I had downloaded about 650GB/608GiB when I tested this during my DRE, at about $6.50). This translates to about $0.005 per GiB, with the first 10GB free. They mention on their pricing page a flat $5/TB/month pricing (they use SI units, so 1000GB = 1TB, not 1024GiB = 1TiB).

Backblaze does not charge for uploads, just storage and downloads. Again, at one point I had over 4TiB stored, with a rough monthly storage cost of about $20 (USD, February 2022). As I mentioned in the abstract, Backblaze B2 storage appears to be quite affordable, and is straightfoward to use.

Backblaze linux server