Not really sure where this goes.  Not really C&R, not really muzzleloader... originally was blackpowder though so that is what I am going to go with.

I have been toying the with the idea of picking up a used (but in nice shape) one.  Any reviews on different makers?  What is a realistically good price?

I have found one rifle on gunbroker for $800, didn't know how a carbine would compare.  Just dreaming at this point, probably not going to be really easy to sneak up on one vs something more popular like a Sharps... I think they are cool though.

You have two choices in a reproduction 1873 Springfield trapdoor carbine.

H&R made some back in the 1970's.
These have an issue with the breech locking lug/cam and how it's is held on the opening lever.
The original design was a one piece unit. H&R made it a two piece held together with a small set screw.
This screw can work loose Causing the action to unlock and fly open upon firing.
Also the guns are not historically correct.

Pedersoli has been making a carbine as well.
The early guns had the same set screw on the locking lug but later version have been corrected.
These are more historically correct.

I've been shopping around for a late made Pedersoli carbine myself. Kinda hard to find.
I even contacted the importer, Taylor's&Co. , and they can't say when a new shipment from Pedersoli will arrive.

Why not just buy a real one? I bought an M1884 Trapdoor Springfield rifle in great shape, and an M1884 carbine from Al Frasca on the US Springfield Trapdoor Rifle Information Center (www.trapdoorcollector.com). I also put together an M1873 sporter, somewhat like the one on his home page. You can get a rifle or carbine with some history, usually for less than one of the repops go for, and they're a bit safer. Yes, you should load only black powder, and the correct bullet, but some people do okay loading smokeless (just be sure to fill the cartridge case with some type of filler after you pour in your BP. Leave no air gaps, especially with the BP.