it does look like a nice vise and Columbian was one of the top companies back when vises in the US were the best around. it's not a huge vise, but it does have the swivel base and the pipe jaws and everything looks to be in good shape from the picture you posted.
i'd pay $75 and i don't need a vise just because it's all there so $100 isn't out of the question especially if you don't see many old US vises in your area for sale. I would check it out to see if any cracks, missing parts or any other issues before buying so pull out the dynamic jaw all the way and inspect it on all sides and take a look inside the vise too.
only question i have is why is it wet? maybe seller tried to clean it up for sale and didn't let it dry before pictures or is that PB blaster soaking on it trying to free up the vise. my guess since it's next to the kitchen sink that it's water, but ask anyway. at least he didn't buy a $5 can of orange spray paint and shoot it all over that nice vise.