Personally I suggest avoiding cheap backup drives like the plague. They're slow, excruciatingly so if you have to do a system restore from one. And the high-end backup software often won't support the cheapies. Nothing worse than having a complete systems failure requiring you to restore from backups except having to wait for 12 hours of tape drive on top of it. This with the president or CEO coming in every 15 minutes wanting to know how much longer.
Grab yourself a decent SCSI adapter and a nice high speed AIT drive. Darn near as fast as some hard drives, totally reliable, quiet as a churchmouse.
Tapes are pricey, but if this data is important, it's worth it.