Product: Bank account or service

In XXXX 2014, we sold a XXXX XXXX on eBay and the buyer paid with PayPal. Although the buyer was local he asked us to ship it to XXXX. We did but required a signature upon receipt of the coin. It was shipped, signed for and we considered it a completed transaction. Two months later, the filed a charge back with his credit card company saying that he never authorized the charge. 
We were notified by Paypal about the charge back after they deducted the {$1000.00} from our Paypal account giving us an {$1800.00} negative balance. At this point, the buyer had our {$1800.00} and our gold coin. We filed a dispute with Paypal saying this was a fraudulent charge back and we wanted our money credited back to our account. In support of this claim, we sent Paypal the following information : An email from the buyer acknowledging the purchase of the coin and stating that he was in the process of paying for it. 
A request from the buyer that we mail the coin to the address he provided in XXXX. We did with a signature receipt required. In the email he asked us to just mail it and he would accept all risk for shipping it uninsured. We declined to do that and told him he would have to pay an additional fee to ship it that far with signature required. He agreed, paid the fee and we shipped it. It was received in XXXX and signed for. Two months later the buyer said that he never authorized the charge. When we contacted Paypal, they first said that the {$1800.00} was a charge for a service and since they do n't offer seller protection for services, we were not eligible for any protection from them. In later inquiries, they said we were not protected because he was n't an authorized buyer on Paypal and then that he did n't have an authorized address. We went gone back and forth with Paypal to no avail. 
They said that they sent the information we provided to them to his bank and that the bank/credit card company decided to uphold the charge back in favor of their customer, so Paypal said there was nothing else they could do and we had to pay back the {$1800.00}. When we did n't, they tried to take the money via an online charge against my business paypal. I contacted the bank and they reversed the charge so I could protect that money. I moved the money out of that account the next business day and set up an XXXX for the company and an XXXX bank account. I had a personal Paypal card which they " limited '' meaning they froze that account and took the {$260.00} in it. Also, after they charged the {$1800.00} back to my Paypal account via XXXX XXXX, they took the funds that came in from my Ebay sales and put everything against the " balance '' they say I owed. We had to stop our XXXX in order to rearrange all of our finances to no longer accept PayPal payment from our customers. We tried to get the buyer 's bank name from Paypal but they wo n't provide it. They said we have to get a subpoena to get it. If we had that, we could go to the bank and file our own claim and show them the evidence. Since I was scammed it has happened to XXXX other sellers that I know about : same guy, same scam against us all. We asked Paypal to approach the bank on all of our behalf but they would n't. It seems to me that if Paypal were to say that XXXX of their customers were seemingly defrauded by this same bank customer, then the bank could determine that it is n't us ; it 's their customer. They would not do this or anything else. We lost the gold coin and our {$1000.00}.