Thomas, were you looking for an original, a reproduction, or does it matter? What caliber do you prefer? Something collectible, or a shooter? You never know, somebody might have one lurking in a safe somewhere.
As you probably know, they were originally issued in .54 caliber for shooting patched round balls, then a lot of them were later rebored to .58 to shoot the standard issue Minie bullet in the War of '61. A good many of them were still later reamed out to be smoothbores for the civilian market, although quite a few of the rifled ones ended up in civilian hands, also. We had one of the smoothbores in the family many years ago, but it was traded off.
There are a surprising number of shootable originals out there, sometimes priced barely above the cost of a new reproduction. Many of these have been "gunsmithed" and/or had the bore relined for competitive shooting, which is great for shooters but reduces their collector value.
I was looking for a shootable original a couple of years ago, and found one pretty quickly. You just need to cast a wide net. Good luck with your search!
Notchy Bob