My wife's battery in her iPhone 4 died and I am looking for a good replacement battery (hopefully cheaper than the $86 Apple charges). I have checked out ifixit.com, digiexpress.com, amazon, and ebay, and was just wondering what suggestions people had? In case someone is having similar issues, I'll share some background on the the problem. Her phone was stuck on the red / dead battery screen. I tried resetting it many times holding the power and home buttons for more than 10 seconds. Occasionally the Apple logo would appear and it would look was it was going to boot, but then it would flash the low battery screen for a second (with the low battery portion being silver/white instead of red) and then the screen would go black. The next time a button was pressed it would display the red / dead battery screen again. I also tried toggling the mute switch and everything other method I could find with the exception of putting it into DFU mode, because there were some videos that hadn't been synced that I wanted to save from the phone. I took the phone into the Apple store and they said it was most likely the logic board and offered me the $149 replacement. Not wanting to lose the videos on the phone I took it home, pulled the battery out of my iPhone 4 and put it into my wife's and it worked perfectly.