Demagnetizing my cartridge? how? how much$$$?

Agree w/Goliverjr! However, if you want to spend more and get a fancier unit that works superbly, try the Aesthetix ABCD-1 for about $179 retail. It is a well-made unit. However, I don't think it works much better, if at all, than the Cardas LP mentioned above.

I've used moving coils without ever demagnetizing with no ill effects. You should NOT demagnetize a moving magnet cartridge. I'll leave the reasons why to the experts.

Jim

For MM cartridge if you de-magnetize the cartridge simply will not work and the magnet isn't going to move.
For MC cartridge you need demagnetizing no often than once per 400 hours or OK not to demagnetize at all since demagnetizing brings almost no difference to the playback.

I bought 3 years ago a used Sumiko demagnetizer and used with my at that time aging MC benz 3i, I listened closely and the first time I used it, it brought a very small improvement to dynamics. After that, I used it maybe twice over a couple years and could then hear no difference at all. I am told by my dealer that it may be best not to use one at all, and not on new cartridges, only on old ones. I do not plan on using it again.