I doubt they will go over 50, actually. With Buffy, X-Files, etc, they cant guarantee as many sales as they can with Simpsons. Simpsons is more likely to sell to casual fans as well as hardcore fans than the other shows are, and it makes sense to moderate the price in order to keep the masses interested. With the other shows (and I agree that Fox is screwing the fans of those shows over), they can charge more because there is only a small amount of people who will buy them and many of them are dedicated enough to spend a lot on them. If they did the same with Simpsons, they could probably sell expensive sets to the hardcore fans as usual, but unlike with the other shows, Simpsons has not so hardcore fans to back on, so it makes sense to moderate the price and keep even the casual fans happy.