A file server will not replace the need for a document scanner/organizer, but instead will be the place that you save all those scanned documents to. The point in getting a file server or NAS device is to centralize your storage.
The way I usually explain this out to customers is to imagine you come in tomorrow and your computer is dead or someone has just stolen it. What have you just lost? What files, artwork, customer information, etc. was saved on that computer that 1) you no longer have and possibly 2) might be in someone else hands? In an ideal situation, there should not really be any company data stored on your individual computers, it should all be located on the file server or NAS so that in the event that one of the end user computers goes down/gets a virus/spontaneously self-combusts, then you aren't out any data, you just swap that computer and you are up and running again.
Achieving this, however, is more difficult that one may think. You have to be sure that your file server or NAS is set up properly to handle fault-tollerance in the event of hardware failures, it has to be properly configured and secured from viruses, outside threats, and inside threats. And for the best performance and efficiency it has to be networked with your computer systems properly to allow for sharing of the right information to the right people, while other information may only be accessed by select necessary people only.
A good NAS device is going to run you about $500 - $600 plus adding in at least two high-capacity enterprise hard drives for storage in RAID 1 for redundancy and continual up-time in the event one hard drive fails. This brings your total to around $1,000 - $1,100. An HP ML110 G7 server begins around the $600 range though to do it with the highest level of fault tolerance, performance, and resilience to allow for continual up time you are looking at quite a bit more:
- HP ProLiant ML110 G7 Server (Part #656766-S01)
- HP 460 Watt HE Common Slot redundant power supply (Part #503296-B21)
- HP P410/256 MB Cache SmartArray RAID controller (Part #462862-B21)
- 2 X WD Caviar Black 2 TB 7,200 RPM SATAIII hard drives RAID 1 (Part #WD2002FAEX)
- 2 X HP SAS/SATA 3.5" hard drive trays (Part #373211-001)
- Windows 7 Professional 64-bit SP1 OEM
Total Approximate Cost: $2,100
The difference between them is that the HP server is running a full Windows operating system so while it requires you keeping it updated with antivirus and such, it is much more user friendly for you to create network shares, back up your data, and you can run additional programs off your server if necessary. Also, you have redundant power supplies in the event that one has a failure the second will continue to run allowing your business to keep running. This has saved more than one of my customers in the past after a power surge or simple failure has taken one power supply offline. Next, you have a powerful hardware RAID controller which is more reliable and flexible for protecting your data on your hard drives.
Just some food for thought. Yes, getting a full dedicated file server can be expensive, and it's not for everyone. However, the benefits that I have seen from having a dedicated file server or NAS compared to just everyone sharing out random files on their desktop computers is immense and the peace of mind alone is worth every cent.