Well given that brand new Bison costs $200 - new old stock for an old lathe type, a used one would be, in good condition, around $100. If it had a nice back then it would be more.
It may sell for a bit more on say eBay but with fees you may end up with a $100 anyways (figure around 15% - 20% for eBay / PayPal fees). The buyer may end up with shipping closer to $200. But you have to wait a while and then do the shipping yourself.