I’ve been using pcloud. They do one time upfront payments for ‘lifetime’ cloud storage. Catch a sale and it’s ~$160/TB. For something long term like backups it seems unbeatable. To the point I sort of don’t expect them to actually last forever, but if they last 2-3 years it’s a decent deal still.

Use rclone to upload my files, honestly not ideal though since it’s meant for file synchronisation not backups. Also they are dog slow. Downloading my 4TBs takes ~10 days.

My 10 year old ITX NAS build with 4 HDDs used 40W at idle. Just upgraded to an Aoostart WTR Pro with the same 4 HDDs, uses 28W at idle. My power bill currently averages around US$0.13/kWh.