If it's based on the older movies, Stern shouldn't have any trouble getting the assets and voice clips for a decent price. I'm not sure what year it changed, exactly, but actors now have to be paid separately for using video and audio clips of themselves from the movie. It was not retroactive, which is why Ghostbusters and Star Wars and Munsters have the goods, and newer stuff like GOTG and Walking Dead didn't. For the older stuff, I believe you just negotiate with the studio directly for the assets.
Note: I'm not talking about drawing an actor's likeness. For that, you've had to get approval on for a long time.