Considering your budget and backup needs, I recommend looking into the Synology DS124 or DS223.
The DS124 is a 1-bay NAS with the Realtek RTD1619B CPU, providing cost-effectiveness with Docker support.
On the other hand, the DS223 is a 2-bay NAS with similar specifications, offering more storage flexibility.
Both models ensure document backup redundancy, and with the potential data increase over the next 10 years,
a 2-bay solution like the DS223 would be a more future-proof choice. These NAS devices are reliable for periodic backups
and fall within your specified budget range.
Considering your budget and backup needs, I recommend utilizing the NAS Finder Tool at [NAS Builder](
https://nascompares.com/nas-builder/) for personalized assistance.
Simply input your preferences, and it will generate suitable NAS options, helping you make an informed decision based on your specific requirements.
This tool is a convenient way to explore various NAS models within your budget range, ensuring document backup redundancy.