I ask this because the purchase will be available to free and subscribed members in the freemium model. But it's exact charge won't be known till the service is completed. Because the user has to accept the a la carte charge before Apple processes it (which requires knowing the charge amount), didn't know if this were possible.
If it's not, trying to ID manners to charge for this a la carte service that do work w/ IAP and freemium (for example, perhaps charging upfront for a pre-paid account that a member can draw on for this service, etc.)
Thanks!
