Building my first NAS server


I’m hoping to get advice on building my first home server NAS. Using FreeNAS with BTRFS or ZFS. Essentially a Synology alternative.

Here are my requirements: cheap (about $500). Support for 8 drive bays (3.5" internal desktop HDD). I don’t need 5.25" drive bays. appvalley

Any recommendations on component parts I need to buy please?