if it wasnt legit and he sold it, he would be in big trouble.
whomever should buy it if anyone does should make some sort of contract/reciept so there not liable for any legal issues.
of course, im naturally not accusing the seller, id have no reason to to trust them but you can never be to carefull =]
I think it probably is legit because you'd be a fool to try sell it on if it wasnt.