A Hong Kong-based company called Brando Workshop is offering an iPhone replacement battery.
Cost: $20 U.S.
Now I am going to save you some squinting.
As you can see in the screencap below, this "iPhone replacement battery" comes with the usual lawyered warnings:
"Please observe all static-safe precautions while working inside of your iPhone. We take no responsibility for damage occurring to your iPhone when installing this replacement battery. If you are concerned or are unable to perform this installation process, please contact a sales representative for a quote on professional installation service."