I have a 6s with a battery problem

Absolutely worth it.

The batter replacement price depends, I guess.

Under this page you can see that out-of-warranty replacement would cost $49, but I would recommend to contact your local Authorized Service provider and find out from them.

iPhone Battery & Power - Official Apple Support

Li-Ion batteries age and degrade. This is absolutely normal.

You have to replace your battery and you'll be fine.

Can you please explain your issue?

Hi

I have the same problem

any idea how much a new battery costs? Does it worth to pay for a new battery?