I'm single. I guarantee I save a minimum of $20 per week on groceries alone. You won't find any savings in dairy, produce or meats, but pretty much anything packaged nets you savings over the big box grocery store down the street.
It's actually pretty amazing how _much_ the difference is for many products. The local (Denver) whole wheat tortillas that I buy are $1.78 at Walmart, $2.39 at Albertson's. Sriracha is something like $2.78 at Walmart, $4.49 at Albertsons. $1.78 vs $2.79 for a can of baked beans. Geisha smoked baby clams or oysters are $1.58 vs. $2.99. Cereal, breakfast bars, snack foods, coffee, condiments and on and on ... are all significantly less. Virtually all paper products are less, as are cleaning products. Toiletries like toothpaste, soap and shaving cream.
I wouldn't go to Walmart to buy shoes or a sofa, but for the sh*t I buy and consume every single day of my life, the savings are significant.