I'd start at $650. Western plows are well built, well designed plows. They are much better quality than something like a Meyers. When I was plowing I was at the local supply house and the old parts guy said that he could tell me all the part numbers for the pumps, valves, and cylinders for Meyers and Fishers, but they almost never replaced anything but old worn out electric motors on the Westerns. My dad runs two of them on his plows and they are about like a Toyota in reliability.
It's hard to find a good operational plow for under $1000 in the fall. I'd wait till next fall and ask a higher price.
x one more for the 3 speed. They really are a lot better for plowing. You don't need the lower first gear and the straight front to back shifting is the s***. And they are damn near free to replace (although a little harder to find) if you do break one.