I might have just added another clarinet to my collection! In my defence; it was cheap and means I don't have to take my good one to work. It also came with an extra (rather nice) mouthpiece and I was after a new one so I am regarding it as having bought a mouthpiece with a bonus clarinet thrown in.
(I say "might", no "might' about it. It arrived today and it's staying).
Very tempted to buy a vintage trumpet I found yesterday in a charity shop on my way home... It had a nice engraving and made in the USA and was in the original case but it didn't have a mouthpiece and I can't remember the brand. I should be saving my money though for a new Alto mouthpiece. I think I'll have to have another look and sneak a photo of it so that I can check it out.
Mouthpieces are cheap, but check the valves carefully. Any significant wear, walk away unless you want it for a wall hanger. Also check the pitch. Plenty of brass instruments in high pitch, or other non-440 pitches. Especially older ones.
In general old brass instruments don't hold their value, due to repair costs.