The value to Apple right now, especially considering that they're operating the battery program at a severe discount.... I unfortunately can't speak to the particular costs of a new battery versus a new phone. It's a lot more revenue for Apple to sell a consumer a new phone than it is to sell them a new battery. We're talking perhaps in the order of magnitude of $100 for a battery before the program versus $1,000 for an iPhone.
On March 1st, 2018. See this statement in context.