Well that gpu is $650 here so $475 USD, then the cpu is $480, so $350USD. That's already over the asking not to mention that's a 570 board, nocuta cooler, corsair psu. These are all great and pricey parts. I get it 2nd hand but still. I'd be asking for at least $800.
They guy my be desperate, or it's stolen or he's just not sure or a scam. I'd check it out fast though and make sure it's all good before you buy it.