No single Walmart in South Dakota had an Air on launch day. Neither did Verizon or AT&T stores. The only stores I came across that did we're Best Buy. We don't have any Apple stores here.
I was able to walk into a Target around 5pm on launch day and pick one up, I was surprised as I didn't think they would have any. The only thing that was hard to find were the iPad smart case and cover, had to go to Apple for those.