If by authentic chips you mean the actual props used in the movie, then you want Roman mold with black bear and red denominations. The $5, $25, $100 and $500 chips - which had screen time in the movie - can be found on
eBay for about $200 per chip including shipping. Haven't seen the $1 chip - that wasn't in the movie - sold for a while.
There have been many replicas made over the years, these are some variations that I know of:
- ASM Rounders, Roman mold, brown bear, brown denoms, same spots
-
CPC Rounders,
CSQ, black bear, black denoms, some with same spots
- TKR Rounders, black bear, black denoms, different spots
- Ceramics