Some of the sets cost more because they are from a franchise like Harry Potter, Star Wars or Jurassic Park. They pay for the brand name and it adds to the price. With Jurassic Park they had to make new molds for various things but other like harry Potter they use normal bricks and molds.
Other sets are Lego's and with those it's all about money. I had a discussion with Lego some time back about their sets getting smaller and more expensive. They told me they had to cover the costs involved with making new molds for the new sets. I said they have most of the molds already, all they need to do was change the colour of the plastic. That was the end of the discussion. they wouldn't talk about it anymore.
