That $29 figure is how much Apple will make you shell out to replace your out-of-warranty iPhone battery through the end of 2018. It's a solid deal, but iFixit points out that you may not want to wait for an appointment at the Genius Bar (or to wait around for the repair to be completed). Additionally, the iPhone 4S, 5, 5S and 5C are excluded from Apple's program.

iFixit's kits are designed such that even beginners can replace their iPhone's batteries, and all the tools are included in the kit. You can peruse the selection here; the iPhone 7 and 7 Plus battery replacements will run you $29, while all older model kits are priced at $24.99.