> Their bill was $1885.43, not $436.77

I understand, I was comparing the storage cost.

Backblaze publishes a cost calculator here: https://www.backblaze.com/b2/cloud-storage-pricing.html (scroll down, it is half way down that page). But it might not contain transactions.

Backblaze does charge for transactions to recoup costs from that sort of thing. But it isn't intended as a "profit mechanism", we believe we approximately break even on the bill for transactions.