I was reading in Making Ghostbusters that Aykroyds origional GB script had non stop ghostbusting. It also said it would have cost hundreds of millions to make it. I think Aykroyd made the GB3 script a lot like his origional GB script in that there would be a lot of busting and very expensive to make. I think Aykroyd said he estimated GB3 to cost over $600 million.