Stashed in: Lolcats!, Japan, Cute!, Gift Ideas!, gifs, It's a trap!, Gift Ideas, Yoink!
You don't want one. They are SOOO noisy that it ruins the effect. They sound like a loud electric motor and gears running. It's a cute idea, but they aren't executed well.
MOW. hrrrrrrm. ghhhrrrrmmmmmmmmmmm. chicke. meow!
ThinkGeek has them. Or Amazon has several versions like the Itazura bank.
Careful, kitty, it's a trap!
Some things were never meant to be.
There's also a panda coin bank: