"Amazon spends more than $90 a year for each Prime customer, losing $11 annually for each subscriber."

"Losing"? If the other stat of purchase volume increasing from $400 to $900 is true, Amazon is buying volume business for just a 1% discount. I wonder how the profit margins skew between average purchases and those which only happened because a customer had signed-up for prime? I recently ordered some collar stays and had them overnighted for $4. Their cost was $20 for what amounted to some little pieces of stainless steel (exactly what I wanted). The margin on these has to be much better than a DVD player.