User blog comment:DancePowderer/How Bounties Actually Work/@comment-3279487-20121218143604/@comment-3425840-20121219082900

It was 300,000,000.

Also even though it seems tough for certain figures 700,000,000 or even higher does seem plausible. Look at Ace, he had a bounty of 550,000,000, now there are people who does have much higher threat level than even Ace, e.g. the Yonkou themselves and Revolutionary leaders. They could possibly have ridiculously high bounties.