I can't speak for the 25,000 dollar chip, but I can tell this story.

One memorable night I had in Las Vegas was spent with Paul Hegge. We went to casinos and he would go to the table in the high roller rooms and ask to purchase chips in the thousands of dollars denominations. You had to see the look on the Pit Bosses faces when he would ask. After they said OK he would count out the money. Later he would go back to his hotel room and scan them for his website hich I don't think is up anymore, but I may be wrong.
Barry