I'll guess that the smaller, Second Generation 639 is a bit more desirable than the larger, First Generation 59.
Some years ago I found a bargain 59 for $290 at my local Gander Mountain. They must have wanted it out of the display case, which I quickly arranged. Some months later, I handed them $375 for a 3954.
As has been said, selling and buying starts with negotiation, and does not become a sale until both parties agree on a price. It is always acceptable to make a polite offer, which can be equally politely declined!
Of course, your mileage may vary...