Well, I have a few tubas, a euphonium, a sousaphone and a helicon. Some laquer, some silver plated. All piston valves, though except the rotary 5th valve on my F tuba. Bores range from .687" to .734" though some old big rotary horns go up to almost .900".
And, yes, they are pricey. Compared to basses, though? I have cello playing friends with bows worth more than any of my tubas, and cellos worth more than I paid for my house. And the violinists........ at Manhattan School of Music, where my kids are in the prep division, the kid who won the Concerto competition last year was playing on a (his father or grandfather's) Guarnarius. So, I don't complain when a tuba costs $15,000 anymore (but I don't buy one at that price, either).
The bow is often more expensive than the instrument and then one might wonder if the bow itself is the true instrument. One of our cellists recently returned from Outside with an ancient $8000 cello, and it does sound good, no doubt about it, but she still uses her old bow. Stringbasses start under $2000, which is why I play that rather than tuba. And my $100 genuine pernambuco wood colored fiberglass bow. The strings cost $200, and they're not bad, but cellists won't touch that brand.