What business are you running that has larger profit margins than 30%?
If your competitors can offer lower prices and still give away 70%, then you're not competitive enough.
create a subsidiary.
dropbox.com, charges $x for 5GB
idropbox.com, a dropbox company, optionally in the caymans, charges $(1.3 * x) for 5GB and has an app.
They've rigged the game.
No, I know of that rule. Just jack the price everywhere --if the iPhone is an important market to you, that 30% is a factor you have to take into account in your overall pricing strategy.
The same holds true for all of your competitors, after all. Either they give up the iOS market, or they have to do the same. So it's not like someone has an advantage over you.
( And, I'd say, if it IS an important market to you, well, you don't get to both have all those customers with their credit cards at the ready in a system someone else built out of thin air AND complain that you have to give him a cut).