I'm an experienced musician (Saxophone), but "just" started playing the trombone (4-5 years now of and on.) So let's say i'm beyond beginner level. In my teens, I played alto horn and euphonium, so i wasn't new to brass instruments.
At least I made enough progression to be able to play in the local wind orchestra.
I play a (borrowed) King 2103f with a Denis Wick 6BY. The shaft of this mouthpiece isn't round anymore, so I'm thinking about replacing it, because (among others) I'm experiencing some strange oscilating effects.
For the rest this mouthpiece feels OK.
I thought to begin with a standard 6 1/2 A-S mouthpiece, because I think my tone still has to develope so it's to early to say which MP works and which doesn't. But an intact MP is preferable I guess

On the Thomann webshop I can buy 6 1/2 A (like) Mouthpieces varying from €22,= to €275 so Í'm curious.
Seems to me that mouthpiece isn't very hard to copy nowadays, so what's wrong with that cheap Startone, Gewa-cup or Arnolds & Sons? I'm not on a really tight budget, but why spend more if it's not necessary?
BTW meanwhile i'm looking for a large bore +F instrument like King 2104F, Bach 42