Comparing Prices at Various Wal-Marts in the Same City

I have always wondered if Wal-Marts in the same city sold items for the same prices or if there was area specific pricing. Well the good people at cockeyed.com figured this out for us! They did comparisons on various groceries (items that would be in an average shopping cart) and found that there was a little variance.

The most interesting discovery, the higher prices were at the stores in poorer neighborhoods!

I also wonder if there is a difference in price between the normal Wal-Mart and the green smaller Wal-Marts. Generally because the smaller Green Wal-Marts are generally in higher traffic areas which I would assume have higher rents. Though, Wal-Mart could easily absorb that cost in order to have a competitive pricing...