.. of the $10 Isthmus chips when I had them up for auction (well, not question the authenticity, but ask for a certificate of authenticity), my response was the same as yours... i.e., that if I were able to counterfeit the chips, I would start making $100 chips and cashing them in at casinos, rather than trying to sell to a much more limited market on eBay. As I recall (and as is probably the case in your auction) the person asking the question isn't actually bidding on the auction, anyway.

Good Luck,

Brent J. Jensen
orbis non sufficit