deals256mb xd-picture card type-h high speed for $18.85


Can someone answer this, why are xD cards so high priced? I mean a SD card of this size(not that you can even find one so very small) would cost <25 cents(I usually figure <$1/GB is a decent price for SD cards) so what's up with xD cards?
I purchased a used Olympus camera and knew xD cards were harder to find and more expensive than SD cards but this is unbelievable(not that I'm saying the deal posted isn't good, it may be but it's still WAY more than a similar SD card).
Amazon sells very few xD cards and it looks like most B&M stores have stopped carrying them too.
I'm just blown away by the cost of the cards and am thinking of returning the camera while I still have time(only got a 7 day warranty). Are xD cards any better than SD or is it just that they are no longer made and are therefor rare?
Thanks for any incite you or anyone else may be able to provide.