It's been 30 days.
File an Item Not Received dispute with the Resolution Centre.
If he cannot prove delivery, either he will refund you or Paypal will. If PP refunds you, they will go after him for the money and there will be a black mark on his selling account.
Do not accept an offer of a replacement. There is no reason to believe it will arrive promptly and you are getting close to the 45 day deadline for refunds.
If he refunds and the item turns up, you can refund the refund by using Paypal's "send money" service.