They have your name. They have your address.

I'm constantly surprised by how petty some "people" are.

There are so many posts of sellers getting angry and acting unprofessional towards low-ball offers or just offers in general.
Yes, we all would like to just slap people that low-ball us. But have you considered your name and address are public domain?

If they really cared to make your life slightly worse, they can make an account that is new and buy from you, thereby getting your name and address for any malicious actions.
Is it really worth that petty "comeback"? Do you really feel that "haha, i gotcha by being mean to you"? Honestly, it's embarrassing.

Be professional, not only because it's the right thing to do, but because it literally protects yourself. Is it really worth that risk?

"I appreciate the offer but my prices are firm."
That all you need to copy-paste.

That recent post on this sub-reddit from that Yeti cooler bag scalper really got me livid. The audacity to be a scalper and give attitude. Well, perhaps they give attitude because they are a scalper, but I digress…