I have a potential customer who has an idea for an ipad application but is unable to find sufficient fundings for this.
One idea that came up is that I do the work either for free or for a minor fee and then receive a percentage of the income from appstore.
How do I decide what percentage is realistic?
How is this affected by the price in appstore and how do I protect myself from the scenario where the customer suddenly decides to offer the app for free?