Unlimited backup for $5/mo to the cloud. FREE backup to other computers using their software which is cross platform on Windows, Mac, and Linux. I'd purchase an external HD(s), backup to it then get a friend to put it at their house. You can adopt the backup on their computer and then backup to their computer (FREE) and to your external HD(s) with their software automatically from your own computer.
Or you can just sync it to the cloud, but 8TB might take a while to get everything up there.