I've effectively become my own Brass Band.
In addition to my Jupiter 470L Euphonium, Jupiter 468 Baritone, Blessing M300 Marching Baritone, No-Name British 'proper' Baritone, 1960-something Conn Cornet, Berkeley Trumpet, and my 1922 Conn Constellation Valve Trombone, I just bought a Besson 600 Concert Tuba. ($322 shipped)
It's a tad rough (the bell, mostly), but my plan is to learn how to roll out the dents and re-laquer the brass - and if I suck at it, oh well... the bell really doesn't affect the sound all that much.
The plan is to be versatile enough that I can play where I'm needed in the low brass section... and right now, we kinda need some tubas. The Euphonium section is plenty strong (usually 4 or 5 of us... but I've seen 6 before).