Earlier this morning the creators of the popular Gmail client Mailbox announced they'd been purchased by Dropbox, but the financial details were a mystery. According to recent reports, however, Dropbox may have paid in the neighborhood of $100 million for the app. GigaOm is reporting that its sources say that Dropbox paid more than $50 million for Orchestra, the company behind Mailbox, with another clarifying that the number was actually much closer to $100 million. Those figures match up with what TechCrunch is hearing as well, with that publication's sources saying the deal was worth nearly $100 million in cash and stock. GigaOm also reports that both Yahoo and Facebook had been talking to the Mailbox team about a possible acquisition deal — though obviously neither emerged as victors. It's still unclear what Dropbox's larger plans for the Mailbox app are, but the company's already teasing potential file attachment integration with Dropbox's own services.