Let's see, 10,000/750 = 13 1/3 units per location, that sounds about right. I think discussion here at MR supports the 'sold out in a couple of days' comment.
Sales have topped $500k? I should say so! 10,000 * $350 = $3,500,000! Even allowing for them talking about wholesale rather than retail prices (as I'm sure they are) they've got to be well
over a measly half-million.
It also sheds some light on the availability, certainly 10,000 is a lot of units, but spread across the U.S. (and a bit beyond
) it doesn't go very far.
I guess this also confirms that the Readers are generally selling well amongst non-MobileReaders.