My old Iphone 4's battery finally wouldn't hold a charge so I had it replaced so I could continue to use it as a Ipod.
So easy its almost comical. The kit I bought had everything I needed and only cost $15.
Instead of getting price gouged by local repair shops, buy a cheap kit, save some money, and spend a few minutes learning something new. I'll be using this site for my wifes old Iphone 5s screen repair shortly.