There were scoped 59/66A1s out there, but few and far between. You can occasionally find the scopes and mounts for sale. Rarely the complete package. I don't know if they are serialed to the gun or not.
The reason for both a scope and a launcher is that when they started manufacturing them with the launchers, they stopped making them without them. The launcher totally redesigns the gun, simply leaving it off would not work...well it would, but it would look silly. If anything, all that weight up front would make for easier follow up shots.
That price actually sounds pretty good if my mental exchange rate is anywhere near the current level...depending on condition of course. Get some pictures if you can.