Facebook is still free - but if you want to message someone who is *not* your friend, it may cost you in the future.
According to the tech blog Mashable, the idea came from some users trying to message Facebook founder Mark Zuckerberg.
Facebook says it's testing to see if people would pay $100 to ensure their message got to Zuckerberg's inbox.
Without paying, the message would likely end up in Zuckerberg's "other" message folder along with a lot of spam.
Facebook is also testing a service that lets people pay $1 per message to route communications to non-friends inboxes.