Did you use a tracked service?
If not, you are not getting any money back from the seller nor any help from eBay/Paypal. EB/PP have a deadline of 45 days on disputes and claims.
You can try going to the credit card your really paid with (PP is just the mediator) and asking the 1-800 customer service rep about a chargeback.
She may need proof of delivery or may accept your proof of mailing.