A similar thing happened at my local WMs, E. We got several cases (over a period of about 3 weeks) of the wave 5 figures (Cobra Trooper, Blowtorch, Hawk, etc), and they sold out quickly (with the exception of Blowtorch). When the WMs restocked, it was with cases of either w1 (Beachhead, Snow Job, etc) or w2 (Recondo, Jungle Viper). Which, sadly, meant there were even more Arctic Destros than before.
I did, however, luck out at Target earlier this week, just prior to their reset, and got the 4 figures from w6 I wanted (first time I'd seen those at all). When I got to the register, they didn't ring up, so they sold them to me for 3.99 apiece, which thrilled me to no end. Kind of disappointed in the Rock Viper, but the others were pretty cool. Now, if I could just find that Money Bag Destro figure, I'd be done with the POC stuff completely.