Binning would not identify a "one in a million" chip that outperforms the other 999,999. They don't determine the maximum frequency / lowest power each individual one is capable of. Look what "binning" implies, they need enough chips at whatever the top bin is to make it worthwhile offering that SKU.
I had assumed it is possible they have "superbins" that aren't on the price list for really small numbers of golden chips if someone like Wall Street HFT guys was willing to pay some insane markup above the highest listed SKU, sounds like that is the case. If someone approaches them with a big enough sack full of cash, something that wasn't worthwhile the day before suddenly becomes worthwhile tomorrow.