~3% plus some fixed transaction fee.

So for low dollar amount charges, like a $1.00 app purchase, the transaction fee can be > 30% (e.g. 2.9% + $0.30 on Stripe).

So selling an App for a dollar using stripe, you get $0.67. With the App Store, you get $0.70.

And for that stripe fee you still have to have your own store, download infrastructure, and website to sell it on. A website that you also have to build, maintain, and market. And you have to deal with chargebacks and customer support during the buying process.

Right, but that stops there

At 1.2$ you already earn more then the Apple Store.

    $ 1.0 Apple: 0.7 Stripe: 0.671
    $ 1.1 Apple: 0.77 Stripe: 0.7681
    $ 1.2 Apple: 0.84 Stripe: 0.8652

So just make it 1.49 and you are good (you'll earn a full 10% more than with Apple)

Anyway even at 0.99 price tag (I think Apple doesn't allow 1$) it only 4.5% less, on a million unit sold the difference would be about 31,710 dollars (693,000 VS 661,290).