I thought I'd mentioned this somewhere but: we have an integration with http://tech4team.fr/arenametrix/?lang=en now.
They do what looks like really good modelling and analysis of sales and price. Once you're all set up, the idea is that you can put in possible prices for a show, and it will take your past sales data and demographic data and data about other nearby competing events and about school holidays and weather forecasts, and spit out an expected sales figure. And then you can vary the price and find the point where your expected revenue is highest.
I imagine it's the sort of thing that if it works for you will pay for itself quite easily.
Let us know if you want an introduction.