I haven't been to Walmart in a while. However, I do buy ammo there since it is the cheapest place around here to purchase 9mm and .45. It also has good prices on .22 ammo, but our local Bi-Mart does as well.
If I want to get ripped off on ammo, (even higher than purchasing on-line) I'll go to the local gun shops. One local shop has .22 Minimag ammo for sale at $10.00 per box of 100. The local Walmart and Bi-mart sell the same ammo for $5.00. I'd certainly support the local shops if they weren't so greedy.