I listen to a pod with some ex Midway video game guys (Team GFB Radio). They worked with George Gomez when he was making video games like NBA Ballers. Anyhow, on one episode they randomly mentioned Gomez hooking a friend up with a Simpsons Pinball Party at direct cost which was about $3,300 at the time.
So a $4,000 BOM on a Stern premium including the game development, parts, labor, overhead, inflation, etc... seems like reasonable guess
Star Wars Pin is probably more like a $2,500 BOM