Do you live anywhere near a petsmart or petco? I generally don't recommend petsmart, but even there, you might be able to find a better food than wal-mart. The foods sold at wal-mart are low quality and most are only rate 1 star foods.
Take a look at
www.dogfoodanalysis.com so that you can read about why those foods aren't good quality and compare them to the 4 and 5 star foods.