Welcome to the forum. No it's not rare, but that is what a model 66 with the box in that condition is worth, so it's a fair offer.
When I said $1000 was a fair price, I was assuming it was unfired or barely fired. That is pretty near the top end for one from that era. Older ones have what is called a pinned barrel and recessed cylinder. Those would probably bring a little more money, but $1000 for a 66-3 is pretty darn goodits unfired