If you buy a battery yourself and try to replace the battery it costs anywhere from $20 to $50. If you take it to Apple and have them replace it it costs $99. It might seem tempting to do it yourself, but think of it this way. If you don't want to pay $99 for Apple to replace your battery, are you going to want to pay $500 for a new one because you ruined your other one by trying to replace its battery. Taking it to Apple seems like a much better deal huh?