Nothing anymore.  Used to go to Price Club (remember them?) and Sam's Club, because we didn't have any Walmarts in California.   Now I can get sane sizes of products at 
Walmart for about the same price per item per ounce without buying the year's supply size.      
Speaking of Costco, I wonder what's up with the class action suit against them......the miffed members who found a LOT of items were cheaper at Walmart, and you don't have to pay a membership fee.