TP: Price is all in what you think is fair and what you can convince the seller to sell it to you for. sometimes there just isn't a deal to be had unless you have to have it and don't care about resale or value.
with the missing chunk off the back slide i'm guessing it might have dropped and maybe with the 1000 pound barrel of concrete adding to the fall. so that is one issue that might not effect the use, but it certainly will keep the value down for resale. now when it is dropped and breaks off a piece of an old 100 year old vise there might also be some other cracks or worse it could have broken the vise nut.
first off before i drove 300 miles for a vise which I've done many more times than i can tell you I would get better pictures of the vise. he might not want to take it apart, but i would like to see the vise nut and underside of the dynamic and screw.
you've bought enough vises to know the value, but since it is a bigger vise you know they don't always come in perfect shape. it might have the static for one you'll find in the future with a dynamic that doesn't have any issues. i'd maybe pay $100 because you've got a half day drive and maybe $50-$75 in gas. hopefully you can get the vise off the stand for loading and the trip, but it would make a great outside vise if you do buy it.
good luck
Dutch: upside down and sideways pictures seem to happen more often when posting on cell phones and not sure why. did you post from a cell? some of the guys swear by Tapatalk, but i usually wait to get on my laptop to post mine. i was going to straighten it for you since i saved a picture of your vice, but Fretters already did that so i'll just say congrats on your find.
SC: that's some price tag for a wood vise. i don't know enough on them yet to say, but for me to pay that much for a vise it would have to weigh over 250 pounds and be in great shape.
ALL: it's rare that i am able to find a good vise on Craigslist any more with all the vise guys picking them up in my area, but i rescued this old Prentiss swivel jaw that weighs close to 120 pounds and paid $40. it might have some parts for another vise i already own because this one is missing the swivel pin and it has a crack on the top of the slide like most Prentiss vises do. it's a beast and i might spend the time and money to make it like new again and only time will tell.