If you want a cheap option try what I did. I have a large full-tower PC case with an older motherboard and CPU I took out of a PC I retired. I have five cheap 2TB drives in a windows storage space. I do not use RAID and it’s not redundant, BUT everything is backed up to CrashPlan small business cloud backup that I pay $90 a year for.

I use this for Plex mostly. It’s been running solid for over two years now. No drive failures yet but if it happens I’ll just reinstall windows and restore my backup, which is probably faster than recovering a large RAID array anyways given how fast download speeds are now.