Yeah and even the expensive ones are not a substitute for another form of backup. There's Mozy (online backup), CDs, DVDs, external hard drives, even multiple USB memory sticks. Anything to duplicate your data storage.
It's amazing how, when things go wrong, your backup method just doesn't seem to be what you had hoped. So, overkill is the answer if you value your data.
Personally, I still use an internal tape backup, I use Mozy to backup the smaller files and I keep a copy of my music on another computer's hard drive.