No, really -- name your price. (facebook.com)

Apparently Instagram’s $500 million valuation sent Mark Zuckerberg into outright panic mode. The acquisition wasn't some secretly-long-in-the-works project. An anonymous source tells Dealbook that within 24 hours of the photo-sharing serving closing its latest round, Zuck was calling up CEO Kevin Systrom, ready to make it rain:

"Mr. Zuckerberg was blunt: Facebook wanted to buy Instagram. Over the next 48 hours, Facebook and Instagram hammered out the details for a $1 billion cash-and-stock deal, the social network’s largest acquisition to date, the people said. By the end of Sunday, the deal was done and announced the following day."

We were kind of hoping he'd just told the lawyers to make Systrom an offer he couldn't refuse.