LOL, yea, ok, so your headtube'll probably fail first
back to the original Q of why are they so hard to get hold off, well that was kinda answered in the first post: "Nearly everyone sings their praises" - demand must of out-stripped current supply.
i have headlocks on all my bikes, makes swapping forks around dead easy, and stops alot of the crap going you the steerer tube. They also allow you to put an extra spacer in if your steerer tube is to short, as you do not run out of bolt length!