I think we do not see too many Super Enchis here in the states for a couple of reasons:

1. They are held back
2. Most folks are combining their Enchi with something else.

Also, when Supers do come up as available the price tag is too high IMO. A double gene snake that has a low as $600 in ingredients that cannot reproduce itself (therefore only lending one gene to a combo) should not cost north of $2K.

Rarity does play in to it, and we will see the price drop on them as more are available (i.e. the drastic drop in Potion prices).