The suggestion to contact Nutmeg Sports is a good one. The owner is Jim Alaimo who coincidentally was the manager of Colts custom shop during the period of the grips. Jim now sells his own production ivory grips. He used to have the tables across the aisle from us at National Gun Day. I think health problems restrict him more to his home turf these days. Jim won't buy your grips, but sometimes if you catch him in a good mood he'll tell you stories.
The market for Colt items has somewhat deteriorated over the last decade. The advent of cheap import clones are partially responsible, as is the overblown price structure. SAAs just aren't worth what people were asking and a lot of them have been tinkered with to make them appear rare or desirable.
I don't think you can find a set for under the $400 price guessed at above. The carving, if done today, would add at least that much. The problem will be finding someone who wants the caribou. Its still better than the dragon's I've got on a set of N frame grips on an RM. My guess is that if you're in a hurry, the $400 will be a good guess. If you have time and patience you can do better. Just don't get discouraged if no one buys them the first day or first few months. They'll sell eventually.
For a background story, my former gun show partner (deceased) had a beautiful SAA. It was modified with fire blued screws and a few other things I forget. But it had a spectacular set of ivories with a carved Marilyn Monroe in her classic pose with the wind blowing up her dress. A very well done carving. She was maybe even "enhanced" as some of the young girls are today...
So along came a buyer. John dug his heals in and wouldn't separate the grips from the gun. And he wanted $3300 I think for the gun. And out of generosity of his heart, he admitted he'd come down to $3200. But the buyer guy was persistent. He wanted those grips badly (I did too).
Then I went on one of my infamous missions across the room. When I came back, the gun was sitting there nekkid. Without a stitch on! The scoundrel had purchased the grips off John's gun. And I just had to hear the story. It seems John had his price (integrity was hard to come by). When the guy came back for maybe the 4th or 5th time, he offered John $1600 for the grips. That was big bucks maybe 8 or 10 years ago. So he relented and sold. Then slapped a set of factory grips back on the gun, priced it at $2000 and sold it later in the day.
You're market isn't as wide open. The country is full of perverts that like MM. You're looking for a Colt fan who lives or romanticizes about Alaska. One with a bunch of money.