So, I picked up a kensington trackball model 64215 for about $2, so I didn't really risk much. It seems to be in pretty good condition, although a little dirty, but I haven't had time to see if it works.
I was thinking of refurbishing and try using it, but before I put any work into it I'd like to know if it's worth it. And I know that the question is kind of subjective but as far as trackballs go, is it any good?