Hello, I'm completely new to Euphonium and just bought used Yamaha YEP-321 (it was cheap), but it didn't come with mouthpiece.

What is the default mouthpiece(one that originally came with) for YEP-321 and how much do they go for?

Also, is there a mouthpiece you'd recommend for a beginner? (prefer same brand mouthpiece but other brand are okay too)