Need suggestions for Backup device

[deh]

Have a Iomega NAS (network attached storage) which has a storage capacity of up to 120 GB.
In accordance with backup strategy naturally Off site storage of all data is necessary. I want it to be able to back up atleast anticipating using up the entire capacity and room to backup more (perhaps auto loader??) also this backup would need to be accomplished accross the network and at a scheduled time (unattended).
Any suggestions of a cost efficient (of course it always comes down to price ;-)) product to accomplish this? I think the major problem will be cost of backup device since the NAS in question was $1,100. It's not an easy task to push a backup device that costs 4X+ more than the device it is backing up. Naturally I go through the "value of backup" speech but the closer the cost of the device to device being backed up the better.

Thanks in advance, have a good day.