what sort of backup are you looking for?
if you want a tape backup then you're pretty much stuck with the expensive DLT tape loader and a lot of tapes, (very expensive!).
ideally if you want to go with a cheaper route, (and assuming that you're only looking for natural disater recovery as opposed to "oh shit I accidentally deleted something" recovery). then I would recomend another server at a different site and synchronising the data between the two servers. that way if one site goes down, you have a second DR site to take over whilst you fix the server.
(this will only defend against natural disaster).
to also defend against user error you'll have to invest in a tape drive of some kind. the only way to avoid spending a few thousand dollars on a tape loader would be to setup another server with even more disk space and have backups made to this that were then zipped, in this way you'll have to buy a load of disks and write some scripts to copy/backup and then zip the data. then another script to delete the backups in rotation.
the last option, -and the least convenient for you. but still reasonably cheap would be to use a USB external drive with a 1TB disk in it.
this is a hell of an expense though! you'd need a new disk for each backup. but you can easily reuse the disks in the same way you reuse tapes...
the trouble is that you're effectivly going to have to buy expensive media to just sit on a shelf.
over all look at it this way.
if you want to do a full backup everyday and archive data for a year,
you'll need 365 tapes/drives (assuming you are happy to say that no data changes over the weekend you can take 104 away from this number) and say you need 261 tapes/drives (the amount of weekdays in a year).
if you take incremental backups for week days and a full at the weekend then reuse the week day media and keep the weekend backups for a year you still need
5 weekday tapes/drives and 52 weekend tapes/drives.
eventually you'll realise that the cost of the very expensive tape drive + inexpensive tapes is far less than the cost of trying to do the same good backups with either another computer, or lots of 1TB hard drives.
basically your choices are.
have no restore path and only mirror live data to guard against the machine dying (you may like to do this anyway). cost $600
make a larger file store and run a good backup strategy, (you'll need about 50TB of disk space for this (52 weekly full backups + space for weekday incremental backups). total cost of this is likely to run into many many thousands of dollars as you'll have to get a decent server with raid, the lots of raid arrays for your disks.
or get a tape drive + tape loader and enough backup tapes, the toal cost being about $10,000. (including the software to actually run the backups).
or you could get an inexpensive tape drive with a low media capacity (say DAT4 ~ 70GB) and get 11 tapes for each full backup, which will probably cost less than the enterprise DLT tape solution outlined above -but will be a lot more hassle to change the tapes!
