If you're big enough that the 30% makes a difference, you're not going to want to risk having your app banned by flagrantly violating the ToS. And even if you ignore that, the extra friction you're going to cause users is going to dwarf that 30% fee.
I've literally spent hundreds of dollars on apps, and generally don't mind forking out $3 or $4 for something I think might be useful. However the probability of me giving some app that's violating the app-store policies my credit-card details is pretty close to zero. I might consider paypal (which I don't even have the details of on my phone), but if there's any equivalent app, I sure as hell will just buy it through the app store.
I've literally spent hundreds of dollars on apps, and generally don't mind forking out $3 or $4 for something I think might be useful. However the probability of me giving some app that's violating the app-store policies my credit-card details is pretty close to zero. I might consider paypal (which I don't even have the details of on my phone), but if there's any equivalent app, I sure as hell will just buy it through the app store.