He's probably selling it for about what he can get at the scrap yard. He says he needs to sell quick so he can move, so he probably doesn't have time to try to get more. And he may not want to see a good machine get turned into scrap. It could well be a real sweet deal. If I was in the area and had room for it, I would definitely get right over there, cash in hand, with no delay.
If you go look at it, please let us know what you find. Try to get the model number and serial number. You'll want to pay attention to the HP rating of the motor. That could be an issue for a machine that big if you don't have 3-phase power.
Cal