Scenario

[glynparson]

With the seller requesting a full refund or you keep the card at the offer. I do not think he was incredibly reputable but neither is negotiating after purchase in my opinion. Had this arrangement been worked out as a stipulation of purchase I may feel different.

[bn2cardz]

My opinion comes from the fact that this was a BIN with best offer accepted. It is possible that the Seller had a minimum that he would let the card go for. Giving a partial refund could put it below the accepted amount he would have let it go for had you made that offer to start with. Because of this I think the seller shouldn't feel obliged to now make up the difference.

Had it been a .99 cent starting bid auction and the bidding got that high, I could see that maybe he could do a partial refund since the card could have been had at a lower price had other bidders noticed the condition of the card also.