For Me It Would Have To Be....
...a set of the USPC Flying Comet Chips that were used in the Big Game Showdown between The Man, Lancey Howard (Edward G. Robinson, playing like a fish and getting lucky) and Steve McQueen in movie "The Cincinnati Kid".
The movie is very dear to me, it started my love affair with poker and the movies. Chipping came later!
With provenance, I'd pay dearly for them!