Ben,
The CalDigit HDElement is ideal for your needs. It's relatively inexpensive, it's easily expandable and it's a true hardware RAID.
Bob Zelin wrote a great post on this a while back:
http://forums.creativecow.net/thread/228/686
RAID-5 is the ideal RAID level for redundancy, capacity and performance.
There is no free ride. If your employer thinks $1500-$2000 is too much money for a safe, dependable storage solution, you're fighting a losing battle. You can't skimp on storage without it coming back to bite you in the future.
Other advice: Avoid LaCie products like the plague.
