Custom in-app billing for avoiding Android/iTunes transactions fees

We are planning a new application development for iPhone and Android devices. The application would be published in both marke开发者_如何学运维ts (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!

We've developed several applications that transport users to a web page payment portal contained within the application.

Apple have seemed fine with this approach, in one particular application we had implemented both In-App purchasing and a custom payment portal - they asked us to remove In-App purchasing as the app was selling deal/vouchers and they classed this as virtual product.... they didn't reject anything about our custom payment portal.

Potentially they could pull all apps that do this at any point they feel like it, although I don't see this as a likely scenario.

Since both Android Market and Apple's App Store terms of service prohibit what you're asking for, the answer is a simple: no, there is no way to avoid the transaction fees (and still remain within the terms of service).

You're also asking about a disclaimer policy -- if you mean for your product, you should disclaim to your users that your app could get removed from its respective market at any time, without any notice (if you decide to implement billing that subverts the market).