Amazon says 1 disc. I say just buy the re-released complete series (now streamlined/crappy packaging with less features and only 4 discs total instead of 9) for $12.82 on Buy.com (free shipping over $25 or pay $3 to ship by itself, add Dungeons and Dragons complete series for another $12.82 to ship free).
UPDATE: Saw the Origins (both He-man and D&D) at Target tonight for $5 each. Not only are they a ripoff, but they put them in a thicker-than-needed DVD case. Cheap but very ugly and incomplete.