If that Colt is gold-plated and not just polished brass, the plating was almost certainly NOT factory. The fit of the sideplate and the conjunction of the frame and barrel show signs of polishing; in a factory gun, the sideplate joint would be nearly invisible. The bluing does not look like the factory bluing, either; it shows too many signs of rounded corners and bluing over rust.
As noted above, the frames were usually nickel plated, with silver an option.
The Sharps likewise is a decent gun but (like most of them) without the silver plating. The frames were silver plated, the barrels blued.
I would pretty much agree on the above values, except that I doubt an open top pocket would ever bring $2k unless it were brand new in the box.
Just FWIW, a note on silver plating of guns in that general era. The plating used was not the heavy silver plating we associate with good quality table wear (Rogers, for example, the company founded by the man who invented silver plating). The silver plating on revolver and pistol frames was a very light plating, often called "silver wash." It's purpose was to look good in the gun store, and it didn't last very long after the buyer left. Even without firing the gun, the silver tended to tarnish and become blue or black, helped along by an atmosphere full of sulfur smoke from coal fires. When the tarnish was removed, the thin silver plate went with it, except under the grips, and often even there when the gun was given a "good" cleaning.