Thomann Euphonium?
Thomann is a reliable online dealer in Germany and somewhat as a price reference here. If somebody sells his instrument, he usually will compare the price with Thomann's price. I'm satisfied with this seller since I've bought some mutes, oil, maintenance material etc. from them. I've read good criticism about this Euph (also in a German music forum) - it seems to be at the same level with the Eastman compensator. Thomann has also an own repair shop.
To get an instrument or give it back is no problem - here in Germany. Thumbs up! But I don't know, what about shipping to US.
Jochen
Boosey&Hawkes Imperial with SM4(U-X),
YEP-321 with DW 4AY ...
... and my cello