In every Wal-Mart I had visited in Minnesota, ammo was typically inventoried behind a counter in locked display cases. This meant that if you wanted to buy some, you first needed to find a clerk that (a) worked in that dept and (b) had a key to open the display. I have waited and waited and waited at some stores to great frustration.
Today, prior to going to a range in North Dakota (which turned out to be a total screw up on my part on time etc.) I stopped at a new Wal-Mart store in Moorhead (well, technically perhaps Dilworth, MN). I found the sporting goods dept and all ammo...everything...rifle...shotgun...handgun...all .... was in shelves where you just take what you wanted to purchase and head to the checkout. A much better experience!
They also had Blazer (brass) 9mm for 8.97/50. That is now my new ammo store. No more waiting for a clerk...no more "we don't sell past 10pm" crap....just put in your cart and head to the cashier.