I didn't see that auction. Maybe they are starting to bring more as newer collectors enter the hobby and don't know the history. I have a dozen or more different raw brass cores from Nevada casinos and I didn't pay anywhere near that for mine.

I believe the cores that were never molded are worth more. You can always take a complete molded chip and dissolve away the plastic to get a core. However, that core will have been machined on the edges, and doesn't have an as-cast finish on the brass edge. My understanding is that collectors who order a special color or color effect on a brass core chip will get one that his been recovered from an actual chip and re-cast. This is considerably easier to do as it requires no machining.