Said he'd take it, and send payment, then GHOSTED

He responded to my ad and said he'd take it, for a small gun accessory to be shipped to the buyer.
I said I'd take down the ad, and await his payment by mail. I did take down my for sale ad.

He said the check would go in the mail the next day.
A week later, and two weeks later, I messaged him saying I didn't get that payment.
My first PM to him got a reply-- he said he was busy and would get the payment in soon.
Two weeks later, still no payment, no response to my last message, and he hasn't even logged-in to ODT in the last 10 days.