I've priced NAS systems ranging from $1,000 to $7,500 and 12TB to 60TB of usable space.
The intended use of these systems ranges from home office to medium-sized businesses and
all of the systems can handle more concurrent users than we will have (200-1600).
My recommendation is to spend between $4,000 and $6,500 netting 30-48TB of space after accounting for RAID mirroring. These prices include the NAS system, 12 hard disks ranging from 6-8TB per disk, and minor accessories depending on the specific system. The two major choices are: