Hi
Not sure about an orchesteral Tuba. tuba.com sell theirs for around 3000euro, is that good?? It feels too cheap to me ;-)
I play an old single Eb Bass ( Boosey now called Besson now they've moved down south ! ).
It cost me around £500.00, lovely tone and nice for just playing along with a piano, probably made in the 1950s, but Boosey always made great quality instruments.
For a professional quality Eb Bass, I'd expect to pay in the region of £5000-£8000 pounds. If I was buying again, I think I'd maybe go for a Yamaha, they still make a pretty good Eb.
Historically, I played Double Bb Bass ( an instrument which you really only find in traditional brass bands), then Double Eb Bass with Burnage Brass Band in Manchester UK, now sadly gone.
There as less and less Brass bands in the North of England

which is a great shame! As the sound is uniquely North of England in many ways. Though the ones left are superb.
Anyway, glad to see there are some of us still around, Tuba or otherwise, its got to be the coolest instrument to play

.
By the way, we need The Ploughboy in tuba section, its a really great piece for both the Eb Bass and Eb Tuba!!!! Easy to play, and to great effect.
Ta!
Greg