Wasabi is much cheaper than AWS as well.
Finally the best solution for backing up your iCloud Photos is definitely Immich. Set it up on your own NAS or a VPS, back up to that, and then back up that server to an S3 storage using rsync or restic. I’ll note that I still backup to Backblaze because its so dang cheap.
I spent months trying to find the best setup a few months ago and this is by far the cheapest.
But still, this shouldn’t be required for normal people. They should get what they pay for.