Well, I made the rounds this morning and...
I picked up Blackout and Spotlight at Toys'R'Us. They had a nice stock of Wave 4, minus Bat Spin and High Five...I also didn't see much of Echo, but a lot of Rocky Roll.
Also of note, I went to GameStop and they had Wave 4 on the pegs, and several Blasterminds ripe for picking.
Plenty of Kaos Traps as well.