I just checked Amazon’s page for the Only Superhuman audiobook, and it says they’ve nearly sold out — only 3 left in stock — and have had to order more copies. That’s a nice thing to see. Of course I don’t know how many copies they ordered to begin with, but demand exceeding supply has got to count as good performance in any case.
And if Amazon does sell out, the audiobook can always be ordered (in CD or download form) from GraphicAudio itself.
Unfortunately I still haven’t managed to get a copy of the audiobook myself. Hopefully that can be arranged soon.