I sold someone a $100 Playboy backup chip 18 months ago. In the description I didn't put backup for some reason. (maybe at the time I didn't know or just forgot) It was not to mislead or scam anyone. I know on other auctions I did call it a backup. The chip sold on ebay for the price they were going for at the time. $600. He emails me and says I did not tell him it was a back up chip and wants a refund. Now the chip sells for $150- $200 or so. I offered him a what I think is fair I would send him back $200. So now he paid $400 for the chip a year and a half ago. He still wants the full $600. Im asking what is the right thing to do now 18 months later. any response is greatly appreciated.

Thanks for reading this
Ricky