iFixit

This is no joke. You can buy a US quarter from iFixit. For three dollars plus shipping. It's ok, it comes in a static-free wrapper.

 

Why would you buy a quarter? Well. You wouldn't if you lived here. But...there are electronics devices that have fasteners that require a quarter sized object, and in fact many were specifically designed with a quarter in mind as the opening tool.

 

Now, obviously you could use any of a number of tools (maybe even your thumbnail) to open a battery compartment, but for some people who don't live in the US and can't find anything better, well, I supposed this deal is for you.