Check out the 'Burly Box' (Score 1)

I know several people personally who have had success with the MacGurus 'Burly Box', you can do up to 1.2TB (RAID 5) for around $1500. See the following URL:

http://macgurus.com/productpages/sata/sataguide_1. php

The 'product page' is at http://macgurus.com/productpages/sata/satakits.php