$300 · DROBO 4D - backup

Data Robotics Drobo 4D, 4 Bay back-up array with USB and FW-800. You can put any hard drives in the bay and the machine will format them. Back-ups are spread across the drives, so that, even if two fail, the whole back-up will be intact on the remaining two drives. Then, just swap out the bad drives for new ones and let the DROBO redistribute the back-ups again. Software and instructions at the link. Four HDD are currently loaded, 4TB, 2TB, 3TB and 2TB and come with the DROBO.