Bernunzio is not a low-priced dealer, but I tend to trust them in terms of claims they make as to what an instrument is. I do notice that the reverb ad say that it was posted over three years ago so nobody is beating down their door for the banjo.
As Bill said that's priced for the collectors market. And that is determined by one thing: scarcity.
The higher the prices the collector can be persuaded to pay the less likely these instruments are to be played. They get cotton-wooled to preserve their inflated 'value' as a financial asset. Like paintings that are effectively hidden in vaults.
It takes all types. But personally I kind've think that the people who buy into that behaviour deserve the self-imposed sterility that entails.