Dan,
Was the rear sight band still there? Your chances of finding a complete rear sight,and toggle, period. Are slim at most. And if you did, they would be very expensive. The only rear sight I have seen for sale, was $200+. And that did'nt include the set screw. The toggle would cost you at least that much. So, I would , as George says, walk away.
However, I don't have Georges affection for honest dealers. So the huggy - kissy thing, is out of the question. A hand shake...maybe.
Ron