There are some pretty cheap tape backup options available these days. The problem is the capacity. Remember that tape drives usually report compressed capacity, and your MP3s are already compressed. For instance, if they say the tape drive will hold 10 gigs, they probably mean that the tape actually has 5 gigs of space.
Here at work, we use DLT backup drives because DAT drives were terribly unreliable at best. But that technology is going to be a little too expensive just for backing up your empeg.
Some things to consider:
1) If you still have the original CDs you ripped the songs from, you can consider that you don't need to bother backing them up at all since you could simply re-rip them in the event of a disaster. Your only trade-off is time/effort there. In that case, you might consider only backing up your downloaded/pirated MP3s. For some people, this is only a small fraction of their collection and would fit on a single CD-R.
2) If your collection isn't going to change in the near future, then CD-Rs, although a hassle, might be your most cost-effective method. A bit of a hassle, but certainly cheaper than buying a tape or another disk drive. The only advantage of tape/disk storage is that it can be easily updated when your collection changes. CD-Rs would be permanent.
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Tony Fabris