I have a 1845 Colt revolver with all matching serial numbers that I’m thinking about selling
Where’s a good place to get it appraised and possibly sale?
Appraised .... that's got to come before the sale.
And keep in mind that a lot of "Civil War" era guns have been faked over the years....
... postwar production guns or even foreign-made replicas have had new serial numbers & proof marks stamped on them. It's a real problem, and takes an expert to tell the real ones from the fakes.