On meat, pretty much regularly better that supermarkets, the odd super sale at the supermarket notwithstanding. I usually buy briskets in cryovac at Sam's, but spares fresh at a local chain supermarket.
On other stuff, it depends on the item. For example, 3 liter bottles of name brand olive oil for around $10. If you go thru a lot of olive oil, great. Or you will see items packaged with additional accessories you won't find in regular stores, and at attractive prices.