Despite the fluid nature of consideration in contract law there are checks to ensure you can't demand $5000 for a single aspirin. That seems like it'd come into

Despite the fluid nature of consideration in contract law there are checks to ensure you can't demand $5000 for a single aspirin. That seems like it'd come into play here. The 30% only makes sense in the context of it paying for more than payment processing, and consequently if the marketing wasn't effective I'd not pay for it.