~~~ $25 chip.

Since you feel Costa won't be offering the chips, I would search from within by making an attempt to contact someone who might have been a casino employee (or know an ex-employee). Usually, contacting any casino employee is done via TheGamingFloor; a forum where casino folk talk... At least you'll get the word out regarding what you're searching for; a lot better (in my opinion) than bidding on some online auction.

I had a few emplyees contacting me when I was selling the Club Royale chips; some wanted only double-face for the chips.

Good luck.