The really important things (essentially only photos) are backed up on a different USB drive and remotely on backblaze. Around one terabyte cost 2-3$ per month (you pay by operation, so it depends also by how frequently you trigger the backup). You want to search for “cold storage” which is the name for cloud storage unfrequently accessed (in other words, more storage than bandwidth). As a bonus, if you use rclone you can encrypt your data before sending it to the cloud.