I mean… I’ve been scouring cast iron at thrift shops for ages.
I’ll probably catch flack for it, but I polished off the bottom so as to be better for my induction cook top. I feel like cast iron+induction was a match made in heaven (though I did have to relearn some old habits, like most people I used the flame height to estimate heat into the pan. Now, it’s quite a bit more consistent, but also a bit more… technical.)
polishing the bottom isn’t hard. an orbital sander, a particulate mask (yes. you need it.). work through the grits. You can do it by hand if you really want to, and you probably don’t need to go beyond “fine” grits. (though I took it to extra fine and then hit it up with green buffing compound because… “oooo shiny.”…)