We've come along way from this, now haven't we? Psychonauts 2 is well established to have been a critical darling, but it was no slouch in the sales department either -- at least if we're to believe this article from The Gamer. And we probably can, seeing as they're really just quoting a tweet from art director Lisette Titre-Montgomery, who refers to the sequel as the studio's "best-selling game to date."
Seeing as both the original Psychonauts and Brütal Legend sold over a million units over their lifespans, that would mean that Raz's latest adventure is in the seven figure range less than a year out. Now granted that's how many copies of Zak McKracken Germany sells in a day, but it's still pretty impressive if you ask me.
Source: The Gamer