Q: Do you have a list of items you buy at Sams/Costco? If so, I'd love to read about that!
A: We don't use our Sam's Club membership often. Originally we joined because we needed a portable resin storage shed--the Sam's model was by far the best value. The next year we needed a computer, and again, Sam's Club boasted many more features on its low-priced model than comparable stores. So anything we've bought there in the last two years has essentially been "gravy"--savings above and beyond the original purchase. If Costco were closer, I would shop there instead of Sam's--the return policy is one of the most generous in retail.
My pricebook tells me that most of the grocery items are NOT best buys, especially for our family of three. We did buy organic coffee at Christmas for a great price, then stocked up when it was discounted in January (Sam's Club markdowns end in a 1, as in 8.81). I am convinced that for fresh produce and meats (most of what we eat), you can do far better with grocery loss leaders or Aldi. I buy the Laughing Cow Light cheeses there at a savings of almost $2.00 per three. Bundles of fresh roses are a staple at 24 stems/$12.99--but you can opt to pick up only a dozen at Fresh Market for $6.99. Generic diapers (available in size 3 and up) cost about 10 cents apiece and come in a convenient huge box. Sam's is incorporating many frozen organic foods, too. When I had to buy blueberries for the muffin extravaganza, I found a huge bag of organic for less than the cost of two bags of Publix brand.
For a comprehensive look at warehouse shopping, let me refer you to Amy Clark's article at MomAdvice.com. It's truly one of the best analyses I've seen. Readers, feel free to add your own warehouse buys in the comments below--I'm sure there are many hidden treasures I'm missing, myself!