But won't a broke person, unable to afford appropriate PPE, probably catch food poisoning, even if they're careful, after handling one in a thousand dead squirrels? If that requires a single trip to the hospital they'll probably be in debt for the next ten thousand squirrels.
Then the ebay listing costs, cost of washing the skull (also borderline impossible unless you have running water), cost of tools to safely butcher, package and posting. Plus the bail for when you probably get arrested on fabricated charges.