Thanks for your help so far.  Let me give some more details and answer some of the points you all have raised.

First, I am looking for cheap and large - and am willing to sacrifice speed to get it. 

Second, I am very intrigued by SnapMirror (replication over WAN) and SnapShot copies (point in time backups).  The reason I don't just build my own little unix fileservers with linux or FreeBSD is that I don't see how GNU tools and scripting can replicate the functionality of snapmirror and snapshot copies.  Maybe I'm wrong ?

So, I see that my initial plan is ill advised - you have pointed out that the disk shelves that NetApp ships are not just JABODs, but have intelligence in them - I did not know that the RAID striping was done in the shelf - I thought all RAID and logic was housed in the head unit and it just accessed big stacks of disks.

So at this point, my questions are as follows:

1. Is there any reasonable implementation of snapmirror / snapshot copies in free UNIX OSs ?  That is, can I get netapp like features out of a normal NFS fileserver ?

2. When I see netapp quote a certain capacity for its filers, like 96TB for the NearStore R200, does that simply mean that they can get to 96TB using the largest currently available IDE drives, and that once larger drives are available that number will naturally go up ?  OR does it mean there is some logical limitation in place on the unit that will keep it from going above 96TB ?

3. What is the absolute cheapest IDE based NAS that netapp has put out ?  Is it the NearStore R100 ?  What if I bought the head unit and shelves from netapp (or netapp branded from ebay), but used my own 400gig hitachi IDE drives ? - I see a 7TB R100 on ebay right now for $78,500 - which is completely absurd.  My 4TB freeBSD fileserver at home cost about $5k ...

Again, many thanks.