I think the battery cycle lifetime that Apple says to expect from the iPhone is approximately 500, I'm not sure of the exact number but it is on there website. From what I gathered when I was looking into this, if you use your phone every day and run the battery down every day, don't expect the battery to last 2 years and be as good as it was as new. Not saying it won't I'm just saying I wouldn't count on it. However saying that, I don't know what the applecare regular costs, but a battery replacement is not a prohibitive expense if it is ever required.
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