We have an Aldi over near where I go to the library. If their milk is that much less than Walmart, I should take my cash over there and buy theirs. Even with the price of gas, I’d come out ahead.
You could try using the Walmart price guarantee. Their new policy says you don’t have to have the ad just tell the cashier whose got it for a cheaper price. I would say that as long as you get the “walmart” milk (i.e. the store brand)that should be acceptable. You can always try and see what happens. That way if you can get it at Walmart you’d save the gas money too.
A lot of Aldi’s merchandise is priced lower than Wal-Mart. We shop Aldis first and then get what we didn’t find there at Wal-Mart.