4 bay nas - backup storage

[Enquiries]

I already have a Freebsd Samba server.

I think I want:
4 bay raid nas:
3x 8tb raid 5
1x 8tb hot spare

just to do backups of the pc's at home
and daily website CPanel backups

I don't know what all the 3rd party apps do but that suggests I don't need them.

I'm struggling to parse through the multitude of options.

I'd like for the solution to be under $200USD but that may be unrealistic.