I have found the following:
TRU : Blister Packs and Cereal Boxes ($4.99 and $19.99)
Target : Gravity Feed packs ($1.99)
Wal-Mart: Short gravity feed packs ($1.98)
Best Buy: hope to check today
The clerk at Walmart thought I was nuts when I bought the whole gravity feed the other day, but I wanted the box, and didn't feel right leaving all the packs laying loose. No golds or sketches, but I did get one of my last missing silvers, my last missing red, a full set of foils, 5 full base sets, and 2 full Wacko-mercial sets, plus extras for sticking and trading. And I wanted Walmart to know that Wackys will sell! I am planning for any future retail purchases to be just bonus boxes or blisters, if those ever do show up at Walmart or Target around here.