There's a big market in replica reproduction Colts, Schofields, etc, and the ammo is freely available, so old but far from obsolete.
As you say, someone wanting a gun for self defence of just-in-case scenarios are unlikely to want one, plenty of enthusuasts do and the market is buoyant. 800 dollars of so gets you one, and a burglar shot dead with one is just as dead as with a modern .40 or 9mm automatic.
Cowboy Action Shooting is a recognised sport in USA and they use modern manufacture reproductions of old West style pistols which must be single action ( manual hammer cocking, not trigger activated cocking). Almost no one outside of CAS or enthusiasts uses single action pistols and these folks usually have a collection inc modern self defence pistols.
In some jurisdictions, esp big cities, black powder percussion pistols such as these occupy a gap in the legislation banning pistols.
The armourer involved is a CAS player. It is generally operated as a very safety conscious game.
As an aside, the guy who grabbed the pistol and declared it "cold" also worked on part 2 of The Crow ( not staring Brandon Lee)