it is a famous name lens for sure. $400? hhmmm? he is not doing you a big favor. on e bay it may go about that high IMO but i woulod guess less. it is not as big as i thought at 1st. there was a similar dallmeyer that went recently on e bay for $504. but it was real real nice with the flange and focus knob. it also covered 8x10.
work him a bit and see if you can get down into the 200 range....that would be better (obviously).
have you been watching on the bay for them to go by.....there are plenty out there.
good luck. keep us posted.