I didn't have one successful auction on eBay because the highest bidders could not pass my very simple verification process. I was only selling $10 to $50 BTC worth at the time. I lost money from all the final value credit refund fees that never covered the auction cost.
What was your verification process?
Send me an email from their PayPal email with a specific message. But since every single winner was using a hacked eBay and PayPal account, they could not. Most just sent a BTC address using the eBay message system or PayPal note after paying and ignored my instructions. I made sure each eBay account had decent feedback so if they won (and wasn't hacked,) most likely I wouldn't get scammed for $10 to $50. I had plenty of safeguards in place because I knew about the scammers. I didn't think I'd get many legit sales so it was more of an experiment since BTC were selling at a premium on eBay.