Just give him the tag.

The thing is.. he has sold the item, you can't just ask the buyer to return it, right? Plus, he isn't going to apologize like he says so giving him the tag is the only solution left for now.

I doubt that he will do so. It's pointless to argue with the seller, don't you all think so?

You've done what you can, mate. I mean by informing us about the failed trade. We all know that how low the seller can be. Giving him the tag is the only solution.

Then, next time just sell your stuffs in the normal way or add in the quick grab option.

emmier has the highest bid and he should be the one that gets that set of speakers since you've stated that there's no quick grab for it when he offers you the quick grab option.