Good Lord, if late 80s is vintage then I am old
The problem with these watches is that the movements are obsolete - the movement in any particular watch may still have many years of life left in it, but when it goes the watch is likely not reapirable.
That's starting to be seen in prices, and it's also a model that sees a lot of fluctuation - I've seen a dealer sell one on bracelet for under $500.
Generally speaking - I'd be happy with $500 - 600 as a buyer, would be hoping for closer to $700 if I were a seller.