Comments like this indicate that the seller is a stupid *******. It's a great deal for the seller to apply toward the purchase of a new machine. It is not a great deal for the buyer.
He claims upgradable to 64GB. You might want to take a look at the required investment to install 8 x 8GB fbdimms. It is a lot to spend on potentially 8 year old hardware. The display is newer, but if the guy used this for his work, that display may have a lot of hours on it at this point. If you say an average of 40 hours per week, it's reasonable to assume it's over 8000 hours. Most displays go way significantly past 10K hours. Some last longer. It could be past that already.
Anyway if something really is a good deal for the buyer, the seller will ensure that the correct information is available and allow it to speak for itself. The people who try to talk up their craigslist ads are typically jackasses.