I have looked high and low, and also gone through a bunch of old Café threads, and it appears that no one on the third planet from the sun produces a US penny containing a magnetic (NOT steel) core. If anyone knows different, please let me know! (Using PK to move a penny is much more believable, in my opinion, than moving a quarter or Kennedy.) Alternatively, can anyone recommend an artisan who could craft me such a thing?

If you are doing PK work why not use a 1943 steel penny and move it with a magnet? If you need the penny to be the magnet I’m sure there is a way to magnetize a steel object. Buy a steel penny and have it copper plated (No body will look at the date, but they may notice the wheat back - So after you plate it — let it get really tarnished).
You may want to talk to some one like Johnson Magic Products... They’ve made custom coins for me in the past.

As a general rule I never tell magicians when I use custom non-off-the-shelf fakes. It will give you something unique only you can do...

Thanks, Tom. I don't want a steel core, however, because I want the "pop" of opposite polarities interacting, which is not something I can achieve by dragging a steel core across the table. Anyway, it seems odd to me that apparently no one's seen a magical or commercial use for a magnetized penny!

I imagine it's pretty small to work with. I bought some copper plated steel 1943 pennies a while ago, but you'll probably have to settle for a quarter. There might be a nickel with a magnet, but never looked.

Just curious as to what other effects you think would need such an item, as opposed to just a steel core coin.

A strong magnet could push or flip a smaller magnet on the table.