I would just backup to an external drive or whatever locally. If you want a NAS, a simple SBC will do. If you really want RAID, get an old optiplex and hook up a couple drives in RAID-1.
For drives, get some CMR WD drives under warranty.
Keep one copy encrypted in the cloud, one offline local, another offsite not overly near you.
Someone send this to Stallman, so he can later download, print and view it at his pleasure.