The place of purchase should not matter for warranty repair. If its still under warranty and Apple determines the issue is derived from the manufacturing process it should be free.
If its user caused damage, it will charge for the repair or replacement.
Apple does not distinguish between repair or replacement prices. It will charge the same fee regardless of what they do. If they can repair it, they'll repair it. If they can't they'll replace it. More often than not, they will replace it regardless of the issue.
click here ➜ iPhone Repair & Service - Apple Support