I know this thread is a year old, but it caught my eye as I continue to search for a replacement for the one I let go.
I don't want to ruffle feathers, but there are a few things about the CS-1 everyone should know. First, if someone bought a NIB CS-1, it's one of the production overruns, not one issued to the Customs Service. The ones that actually came from the Customs Service came in two versions, 3" and 4". When they began to covert from revolvers to the 9mm semi-automatics, the revolvers were being destroyed. Someone was able to stop the destruction before they were all gone, leaving about 1500 of the 3" models and just over 2000 of the 4" models intact. The 3" model is the more desirable version having a satin stainless finish, 3"-barrel, adjustable sights, and sporting Pachmayer Compact grips. The last one I saw sold on Gun Broker for about $2400. The government isn't known for storing cardboard boxes, so having an original box is rare, and if it was a true CS gun, the box would no doubt have some sort of accounting code from the agency on it. Few that I've seen have the original grips, in fact the one I had had Hogue Tammer grips on it. I switched those out in favor of a set of Hogue Bantum grips. I'll see if I can find the pictures of mine and post them up.
I'm also curious if the OP's gun lettered.