We are planning a new application development for iPhone and Android devices. The application would be published in both markets (Android Market and Apple's App Store) and its download would be free. Nevertheless, the application would have some items that can be purchased by the user. The easiest way would be to integrate each version with its corresponding billing system: Android In-App Billing and the Apple iTunes Billing System.
Is there a way for avoiding the 30% transaction fee from the billing systems? Can a developer use a custom in-app billing system for its application? Is there a disclaimer policy for Android or iPhone when using other in-app bill systems for avoiding their transaction fees? What are the options a developer has for providing an in-app item purchase within his application?
Many thanks!