Back in the 70's & 80's I had a guy that bought Quill and Guard Hair from Porcupine, Weasel pelts, Sculls, Weasel and Coon peckers.
He passed away and I never looked for another avenue to sell. I just don't see Porcupines in my traps, in my area.
Big Cat, there is still a market for quill & guard hair (or about any animal parts), but you will have to do some work to find a buyer, but they are out there and still using Porcupine for native American items.