At $139, the price Apple charges is grossly inflated. The battery itself is worth about $10-20. $70 for replacement sounds about right. (I know someone who recently had the screen and battery replaced in their LG phone for $100.) The main issues with batteries is with suppliers who sell poor quality knock-offs, or seconds or old stock that were meant to be discarded. They sometimes crop up on places like eBay. A reputable local dealer is unlikely to be selling those.