The charge is part of a test of a system introduced in December, charging $1 to a sender for a message to reach the Inbox of a Facebook member who is not the sender's Facebook friend.
Facebook members who want to reach VIP members with large numbers of followers who are not their friends -- including Zuckerberg -- face the higher $100 charge, Britain's Daily Telegraph reported Friday.
A Facebook spokesman confirmed the $100 charge was part of the test, currently only running in the United States.
"We are testing some extreme price points to see what works to filter spam," he said.
Facebook focused on the spam-fighting aspect of the test when it was introduced.
"Several commentators and researchers have noted that imposing a financial cost on the sender may be the most effective way to discourage unwanted messages and facilitate delivery of messages that are relevant and useful," Facebook said at the time.