You don't need both Billing and Invoicing. Invoicing is for one-time payments (typically after a service has been delivered), and Billing is for recurring payments.
All in all, we're looking at $0.30 + 3.4% (or 3.3%). This is clearly lower than 30%, except for very inexpensive apps (~$1.29 or less).
Stripe Payments [1]: 2.9% + $0.30
Stripe Billing [2]: 0.5%
Stripe Invoicing [3]: 0.4%
[1] https://stripe.com/pricing
[2] https://stripe.com/billing/pricing
[3] https://stripe.com/invoicing/pricing