Definitely open a dispute and where you don't know this person at all, I would escalate to a claim ASAP. This will prevent them from pulling any money that they have in their account (just in case PayPal gives you a refund). Unfortunately, buyers are not AS protected when they buy privately (rather than on Ebay - Ebay and PP are partners).
Something that is really important is how you paid - I can't remember what all the choices are, but I know when you checkout you can choose between "goods," "personal," etc.
When you file the claim, I would put it as "item not as described." Hope this helps and good luck!