They are valuable to stupid people.
First off, Black Talons were never designed to work well at 9mm weights and velocities. They were originally intended for357 magnum and 44 magnum type applications, as hunting rounds, etc.
Because they were black and unfolded into a 'talon' people thought they were uber-special, armor penetrating, and a whole lot of other BS.
Winchester rode that wave of popularity for a while by putting black talons out in all sorts of combos.
Of course the antigunners eventually put a ton of pressure on winchester about black talon. I don't recall if they were made illegal everywhere, but many municipalities enacted restrictions on them. I think winchester could have sued and overturned these laws, but they didn't
What Winchester did was bring out the Ranger SXT...which stood for Same Exact Thing, they just colored them metallic yellow rather than black.
Since then Winchester has actually improved it's SXT line, making them perform better at lower weights and lower velocity, so Winchester SXT is actually a good choice in 9mm.
So anyone who is paying a premium for 'black talon' is being stupid.