GrayAmp is free, if you can find a copy anywhere, as it seems to have gone from <http://www.mp3machine.com/software/GrayAMP/>

but there is an r18c3 version :) at
<http://www.rogueamoeba.com/~qdc/pub/os9/GrayAMP_r18c3.sit>

VersionTracker also suggests:
<http://www.versiontracker.com/dyn/moreinfo/macos/7984> <http://www.versiontracker.com/dyn/moreinfo/macos/9179>

Haven't used any of them myself.

Have fun,
Shay

You can still get grayamp at:

http://www.hitsquad.com/smm/programs/GrayAMP/

However I prefer(ed) winamp mac due to its speed, it opens streams (a bit), but mainly it's playlist.
I even used it live on an old 6100/66 OS8.6, so it's tough too:

http://www.versiontracker.com/dyn/moreinfo/macos/10209&vid=7452

Creating new MP3s wont be as simple as iTunes though.
Theyll need to be done with something else.
Try www.hitsquad.com, www.versiontracker.com etc.

Good luck
Paul