head shell for Sony Biotracer arm?

I was wondering where to buy a new head shell for Biotracer arms made by Sony? Thank you all for your responce.
I have many bio units, and on most the head shell is different.
I have some extras that I acquired from units that were sold for parts. I did look for NOS, but to no avail. The hardest to find are the 800 and 555. So, between CL and e-Bay a parts unit should show up, but may take months.