Run and get one or the other. Those are bargain prices! LNIB G26/27 around here go for $450 and NIB G26/27 go from $500-$600. I wish I could get a NIB G27 for $400.
I'll confirm the prices again, and let you know. They had a price sheet of their inventory items and I checked them both out, along with the HS2000 ($300 NIB).
Funny how a hundred bucks difference can put a damper on things!
If the G26 still looks brand spanking new, $400 isn't really a bad price. I think $500 for the new G27 is a bit high. I would definitely bargain with the guy to get a lower price and see what his cash "rock bottom" price would be. I'd bet he would take $350 for the G26.