I have memberships from both Sam and Costco. I do not buy clothes from them since I go to Banana Republic or Dillard or Macy' etc... to buy these. I don't buy cosmetics or skin care products since I go to different places to buy them. I don't buy groceries from them since I go to Whole Foods, Central Market or H-E-B from them. However, I bought all of household items from them.
I compare prices for all my household items: liquid dish soap, laundry detergent, plastic wrap, Foil wrap, Toothpaste, Toothbrush, Water, Paper plates, paper bowls etc...
All of items I bought Sam has much better prices than Costco. I am very surprised when someone said Costco is better than Sam in this field. I am not related to any of them and this is my 2 cents.