The PA1X does include a Hard Drive. It is not an option but rather standard equipment and the price has been posted by Korg USA here in the US. What I've posted is Korg's Retail and MAP price. Usually, the selling price is Korg's MAP price.
There are no PA1X keyboards available yet. Stores with mailers and internet sites have started listing the keyboards but they have nothing available yet.
George Kaye
Kaye's Music Scene
Reseda, California