Where or what kind of battery can l get to replace the one in my Pokewalker?

Question

I want to replace my battery on my Pokewalker for having it for over a year, and it finally gets the blinking battery symbol in the corner.
This means that it's battery is about to die l guess... but it's been like two weeks!
Anyways, eventually, this thing is going to die, and l want to use my Pokewalker FOREVER!
Does anyone know where l can get battery replacements for cheap (because l don't know what kind of batteries the one in the Pokewalker is, it looks like a watch battery).

Answer 1

Pokewalkers use clock batteries is guess so, go to any store that sells that

Answer 2

CR2016, CR2025 or CR2032. Not sure but the difference is small...