The real money in electronics is in accessories. People will pay $25 for a Raspberry Pi and fret each additional dollar, then turn around and pay $20 for a injection molded case for it.

If their strategy is to sell accessories then they $9 could be subsidized in that way.

If you're like me, the $9 gets you in the door, then you load up your cart with everything you want and start thinking about the total price at around $100.

Under $100 I think the typical "has a day job at a startup" technologist is not going to think twice.

They just need to have enough compelling components to get the total order amounts up there.