You are also likely to find them at such Vintagers gatherings as The Southern SXS next weekend or the Vintage Cup in September. Note that these things don't seem to have quite as good a survival rate as the guns they came with. Ergo, they are scarce and getting scarcer as Vintagers rebuild cased guns to former glory. Double ergo - think expensive for what you get. Named snap-caps, too. Oh, yeah - named cartridge magazines are a wee bit on the salty side.
Oh, the joy of going broke trying to look like you were an 1899 high volume shooter who just walked through a time warp. But then, that is what costume parties are for - and you get to shoot at this one.