Concerning the Lian Li v2100, i can't recommend it for big storage. I have mine running 12 hds for now (i added 5.25 --> 3.5 converter bays so the enclosure maxes out at 21 hds & DVD drive)
The HD compartiments only have one 12cm fan... for 12 hds. this is enough for the 6 hds in front of the cooler, but the 6 hds behind the 6 first arent nearly cooled enough. they overheated for me.
That's why i moved towards a Chenbro Rackmount a few months ago. They're expensive, but not by that much, if you build them yourself. My 4U rackmount with 16 hot-swap S-ataII bays was around 600 euro, with a seasonic 600w powersupply.
I added a server mobo from asus to it, a gig of ram, and a cheap amd64. Raid is done by an areca 16port pcie8x card.
This would get you to a total cost of around 2000euro, but without any harddisks. Seeing that 320gig hds sell for around 100 euro here, that'd add 1600 bucks for 5120gigs of hd space... roughly the 5tera you wanted.
Hope that helps a bit