These come up occasionally on eBay. I set up an alert and managed to buy one about a year ago. Since that time I still monitor for a spare and have seen 1 for an outrageous amount. Quality wise the NTK seems identical for 1/20 of the price but I had a misfire issue above 3000 rpm and the Mopar unit does not so it was worth it. The one I bought was not “vintage” packaging either so it does seem like newish parts are still being supplied in limited numbers which would explain the cost.