What about Sterns research and development costs ? They can't just instantly drop prices dramatically. It's not realistic. They also have to pay for a new factory which is three times the size. Someone has to bear the cost of the millions upon millions it's all going to cost. All these new staff for the design and manufacturing team aren't going to be cheap either.
Also, I have played the Mustang Pinny and it is far from a lemon. It's a excellent Playfield and a very enjoyable game. Not every game is going to sell like ACDC did. Mustang is an outstanding player.