how to price of apps in app store

If the app is not "free" (i.e., free to download) it will display a price on the button you tap to download it. If the App is "free" that button will display "Get."

to see if the app has charges after downloading, tap on the app in the App Store (don't tap the Get download button) to see details about the app and then scroll down to the "Information" section and tap "In-App Purchases" to see information about what in-app purchase options they offer.