You ink should give him back the $18.11 for the item and $3.20 for the sipping back to me the old one?? Can ask him to send it bck to bugdig for me? as it is between eBay, paypal and shipping cost already costed me $60!
If you want, you can ask, but you sold him a defective item, so even if it's not your fault, ultimately it's your responsibility. If you refund the money, you'll be left with the extra ink, so you can sell that to recoup some of the money. You can also ask BuyDig to give you a refund instead of shipping a new ink.
Like I said, #CostOfDoingBusiness.