Sometimes it’s difficult to discern whether or not your business model needs to take into consideration a 30% cut for an in-app transaction. To that end, I really appreciate this take from Joe Blake, which I’m paraphrasing for clarity:

If any content is being delivered to the iOS device because of the transaction, then Apple will take its 30% cut.

Further, Apple’s policy states:

Do not use (the In-App Purchase API) to sell real-world goods and services.

In this case, you’re free to manage your own in-app payment processing system and forgo any app store transaction charges from Apple.