oclv99-
For the basic drive, it's $1+, with many in the $5-$10 range, depending on which partner. I know it sounds vague (how many is many?), but Steven won't get more specific than that. At the shareholder meeting, he said more it would be more than $1, less than $10, which is equally vague.
For upgrades, I've heard a low figure of $25-$30, but I believe $50 is the most widely quoted number overall.