I've only seen Lowlight once, at a Walmart here in Calgary. I've seen Skydive a couple of times, also at Walmart, so they are out there.
Shadow Tracker and the new Destro were not in the revision cases that shipped to the Walmarts, so you will probably only see those at comic or toy shops (not TRU... yet). I think the case breakdown was as follows:
Low Light x 1
Sky Dive x 1
Alley Viper x 1
Jungle Viper x 1
Storm Shadow PoC v1 (with all the ninja gear) x 1
Beachhead x 2
Snake Eyes PoC v3 (with the 2 heads and elastic webgear) x 2
Duke PoC v2 (with pulse rifle) x 1
Shock Trooper x 2