I've blown more money on worse

The stand seems kinda funky to me, to extend the headstock end without support may end up causing problems. I'd probly build another or put it on a sturdy table or bench of more proper size. Maybe you could offer the $300, and if he balks, let him keep the stand if he'll sell the machine without it. Either way, I'm with Pete, $300 seems like a pretty good deal.