http://resolutioncenter.ebay.ca/
You only have 45 days to open a Dispute.
If the seller cannot prove that the item has been delivered, and he does not refund you , Paypal will return your original payment and go after him for their money. He will have other fallout ((evil laughter)).
But if more than 45 days have passed from purchase, go instead to the credit card you actually paid with (PP is just a convenient mediator) phone the 1-800 customer service number and ask about a chargeback.
Again, even cards have deadlines so act promptly.
In future, allow 30 to 40 days for the item to arrive.
Contact the seller ONCE to let him know the problem.
If he doesn't refund (and an offer of a replacement is NOT satisfactory because it will not arrive either), go to the Dispute immediately.