(Dujon) Nah, it was a load of King 3B's. Pricey, aren't they? Mine cost £595.

The day I realised that my musical skills would never lead me to buying a musical instrument, brass or otherwise. It was the brass involved that disillusioned me.

(Duj) Musical instruments, especially new ones, are a ludicrous price and there's a lot of pretentiousness involved. The keys of a bassoon, so I was told by a bassoon player, are made put of silver. Why silver? Brass would do, or chrome-plated mild steel or even cast iron or even nylon, which is strong stuff. It's all bollocks, I tell you. Everything is. I could go on.

I would postulate that when it comes to the quality of metal, we are talking about the difference between a responsive brass instrument and one that has as much life in it as a 3 day old dead ferret. Like my French horn - complete crap, but then so am I as a horn player so it doesn't matter. There are, however, cases where it matters very much. Like real brass players.

(Pablo) The quality of the metal probably reflects the overall quality of the design from an engineering point of view but should not affect the actual tone since all the sound comes out of the bell and the material of the instrument itself hardly vibrates at all. This obviously does not apply to an instrument with a sounding board such as a piano, violin or guitar but it certainly does to a brass instrument. You can make a "brass" instrument out of anything, even cardboard. A metal mouthpiece probably helps though.
The worst thing about a cheap 'n' nasty trombone, say, is a sticky slide or leaky water valve, engineering defects. If you open the water valve some notes just disappear; they just cannot be played whereas others are completely unaffected. Weird! All to do with nodes and antinodes.