Just realized this while scrolling through Koss replacement pad listings: those foam side-pads where the Porta Pro headband rests against your head above the ear look a heeell of a lot like Dekoni nuggets! 
Of course, each one is 1/3 the size of a Dekoni nugget, but maybe that’s a good thing: more versatility, better for thin headbands, and easier to buy fewer of them if you don’t need the equivalent of a Dekoni 4-pack. Also probably cheaper, depending on where you get them, e.g. at this price ($4/pair) if you cover the same area by buying 6 pairs you end up around the same price as what I’m seeing for the Dekoni set on Amazon atm: Remplacement Bandeau Mousse Pad Coussins Pour Koss Porta Pro Portapro Stéréo Pp | eBay
But then you would save on shipping and taxes, or maybe you don’t need as many.