Buying resource mines from minors
I'm pretty sure I've seen more than a few mentions around here of players buying resource mines. I've never been able to get a reasonable deal together with a major civ, but I've mostly put that down to my near-complete. But in my current game (TA 2.0), I've gotten past 250 turns and *all* eight of the minors I started with are still there. And they own lots of the mines. And those darned things aren't even on their trade lists!
When I started trying to shop for minors' mines, I thought the situation was because my diplo skill was barely above par (if that) and my military was distinctly bottom tier. But by this point, I'm clearly ahead in the arms race and have "incredible" diplo compared to the minors, plus the Galactic Bazaar.
Is it possible that the minors are simply *never* willing to sell a resource mine?