Realistic selling prices for pre-war Tubaphone tenors are perhaps $600 to $1000. We see them listed for more, sometimes much more, but those sit on the market for years without selling.
In all fairness, they "should" bring more, considering the quality of the instruments and the price of new tenors that are of lesser quality. But the price of used instruments is not necessarily dependent on the quality of the instrument.
What Bob said. I've owned two, and I think these are great banjos. A couple of things to consider. Is there a resonator? Are the pegs the original friction tuners or have they been changed to a modern version (imo very desirable) and if so was the replacement done well. How are the frets, and is the fingerboard pitted. After all, the banjo is almost 100 yrs old. Check the classified on BHO. The one currently for sale has a smaller pot, and for some the larger pot is more desirable. The 10 15/16 pots have 28 hooks, the 11 13/16 pots have 30. The original necks are NOT slim, but that may not be an issue for you. Recently, Bernunzio had a 19 fret version with resonator asking $1500. That is the highest number I've seen. It did sell, final price unknown. I've seen some very nice ones go over the last 6 or 7 years from $750 to $1150. Hope this helps.
I picked it up, not without noticing some of the cracked lamination in headstock. Got it for less than $400. But the rest of banjo is in very good condition, frets art good, a 12" tubaphone! Wow. Those Vega banjos are very well built.
Original tuners. Not planning to replace, they are friction but stay in tune. I just need to work on the headstock lamination.