NAGATRON HV9100

Hello all, years gone by I worked for Marcof, some of you may remember the moving coil head amps. At one time Nagoaka asked us to develop a Head Amp for this cartridge. They sent us one, we did a few hours of testing, but only 2 or so hours of listening. So I have a Nagatron HV9100 Ribbon phono cartridge in mint condition in its original box and it is completely spec'd out with full graphs....
It has been gone so long.... Thinking about selling it off, anyone out there have an idea of its value? If it is worth much, I'll list it for sale here, If not, it has been resting fine. Thanks for any replies. Tim