I bought a Selman black curved soprano from ebay a few years ago. It plays in tune, and has that sweet centered sound that I like from a soprano. It seems as long as the basic construction of the horn is sound, and the intonation is true from bottom to top that is a good start. I added a Claude Lakey soprano mouthpiece, and some Vandoren reeds (2.5) and that baby sings.
It was really cheap, but plays like a champ.
A lot of what the horn actually sounds like is totally dependent on you though. I haven't seen a magic horn that plays by itself yet. Like an old friend told me once. It's not the arrow, but the indian.
There are a lot of great horns out there for sure.