eBay and Craigslist finds

Pay for it with paypal first. He might send it to you anyway. If you leave neg feedback but don't pay, he can start a non payment claim against you. You then have to appeal to have the non payment strike removed from your account. Although the messages between you prove that he is at fault, the effect of the non payment claim is that all feedback is removed for that transaction.
If you pay first, he cant start the non payment claim and your money is safe if you pay with paypal.

I've just declined the cancel, and havn't paid anything. Also reported the seller to ebay. awaiting what they say.