About 15 years or so ago, Dixie quietly started buying up original Trapdoors.
They were ubiquitous at the gun shows, and as a result - fairly cheap.
Then - someone noticed the buying pattern, and prices rose, and reference books got themselves published.
As a result, there really aren't any 'shooter' Trapdoors now, as folks are collecting and restoring them - and since restoration is pretty straightforward, there's little to worry about, unless someone decides to fake a carbine - so anything that's found will be just that - 'found'.
Replicas were made by Harrington & Richardson and are made by Pedersoli, but you pay a price that's commensurate with originals at times.
Nevertheless, there were an awful lot released to the public, and closets and attics abound, so put out feelers locally to see who might have 'what' and you may be pleasantly surprised.
Good Luck.
Vaya,
Scouts Out!