If you buy something NEW at half price on eBay with free shipping, when everwhere else it is selling for twice as much NEW, it is fraud and you will be receiving stolen goods.
The eBay fraudster sets up a new eBay account, perhaps sells a few yard sale items to get some good feedback, and then starts his fraud. First of all, his contact info is bogus. You cannot contact him at his address or phone number. Second, he has a fistfull of active stolen credit cards that he probably got off the dark web. He is probably also using a fake ID to cash his checks that he gets from PayPal.
Fraudster puts up a popular item on eBay at half price with free shipping, with an inventory of 10 or more. As he sells out that item, he orders the goods from an unsuspecting website using a stolen credit card, shipping the goods directly to you. The victims are you, for receiving stolen goods, and the website taking the stolen credit card.
The fraudser even knows that the billing address will accept a credit card on any website if he puts in the street name with a bogus street number and leave out the apartment number if there is an apartment. Credit cards match only on street name, city, and zip. This makes it impossible to track down the billing address to find the person owning that card to check if the charge is valid or not. The website may have an IP address for the order, and that is all.
You have no recourse if you get the goods and the police come to your door to recover the goods. The seller is using fake contact info, so impossible to report him to the police. The seller has his money, and has already pulled out his money from his PayPal and cashed his checks at a check cashing service. You have no idea where he lives. eBay will not file an FBI fraud report or give you info about the seller due to seller protection laws. The most eBay will do is suspend his ID. Once his eBay ID is suspended, he opens another eBay ID under a different fake address and continues his scam.
One clue to the fraud is if you look at the order confirmation in the package you get, and the eMail address is not yours. You should immediately tape up the box, refuse the goods, and send it back to where it came from. Call that website and let them know it was an eBay scam. Call eBay and report the scam also.
Fight back to stop this fraud!. If you are the website that was victimized with a stolen credit card, look at the IP address of the order, verify the billing address, and look at the email address. You can detect fraud by looking at that info in the order. Mail a coy of the order with a letter to the shipping address that you did not ship because you found fraud. Instruct the receiver to refuse any stolen goods from any other websites for that eBay item.