Hit the Goodwill and Salvation Army stores, and any other thift stores you can find. Old cast iron cookware seems to find its way to those places quite regular-like. I used to have a nasty old 22" cast-iron griddle for years, and couldn't ever see myself using it so I finally tossed it. Now that I have a beadblaster, been kicking myself in the ass ever since.
Funny, I've talked to a few locals that would likely have what I'm looking for. They all said the same thing. "Used to but tossed 'em. "
Hard times make strong men
Strong men create good times
Good times create weak men
Weak men create hard times