We discussed a while back that these were at Toys R Us UK.  Well, now they have been spotted state side.  Although the only ones spotted were the Mechanical Masters, and they had dinged corners from shipping.  The wave breakdown is below so we can only assume thats why they are still on the pegs.  It looks like since these contain a comic, people want them in minty fresh condition.  The others in the wave include the female Thor and Sam Wilson as Captain America.  I don’t recall them in action figure form yet so this could be why they were snagged early.  No reason to worry, they are not a Toys R Us exclusive and you can pre-order a set here. 

Wave 1 breakdown:

3x MVL SHIELD WIELDING HEROES
2x MVL DEFENDERS OF ASGARD
3x MVL MECHANICAL MASTERS