$0.10 per CPU core hour. This covers the actual CPU time an application uses to process a given request, as well as the CPU used for any Datastore usage.
$0.10 per GB bandwidth incoming, $0.12 per GB bandwidth outgoing. This covers traffic directly to/from users, traffic between the app and any external servers accessed using the URLFetch API, and data sent via the Email API.
$0.15 per GB of data stored by the application per month.
$0.0001 per email recipient for emails sent by the application

mailは何通まで？