Porcupine guard hair sells for $10 - $15 per OUNCE. (of course a porcupine only has about 3/4 ounce of guard hair on them)
Procupine quills sell for pretty good money also and even their claws are worth something. Their skulls bring decent money too.
Hope you haven't just been throwing them away, with a little work a porcupine probably is worth more than the coyotes and foxes you are trying to catch.