Well, seems they might make margin on accessory and postage etc, however, the math seems pretty clear -- they /can't/ sell it at $9 and break even, so there has to be a trick...
Personally, I'd rather give my money to guys like Olimex anyway -- a notch more expensive, however these guys are /spotless/ at making everything as open as they can, and in fact, they probably 'suffer' for it as many companies seem to use their (open) designs commercially...
https://olimex.wordpress.com/2015/06/05/how-to-get-in-the-ne...