You people Erk the shit out of me. You don't read. You make grand assumptions. And try to make a seller look like an ass with no supporting evidence what so ever.
His time stamp is valid. And hes asking 6 btc. So no it doesn't sound like he paid 5 grand for a miner and isn't using it. It sounds like he payed around 2k for it as he's producing a profit at his asking price of 2,500. Maybe he paid 2,500. Who knows. What do we know? It doesnt fucking matter. If he proves it works to somewhere near the advertised hashrate its really none of your business now is it?