We have a membership, and find it incredibly valuable for a few things, with caveats. Base line: for what they sell, we find that it's about equal to slightly more than our grocery store's sale prices, but the stuff is actually available at almost-sale-prices all the time, so if you're not interested in stalking 3 grocery stores weekly to combine sales (and spend more on gas than you save...) then it's a good option. But keep a strict list shopping list and STICK TO IT, otherwise it all goes downhill really quickly.
Valuable for:
- DIAPERS omg (ok, you can equal the price IF you get Amazon Prime, but I'd rather deal with a company that treats it's employees well for the same consumer cost, personally)
- Staples: flour, sugar, butter, oats, rasins, nuts, cocoa powder, baking soda, yeast, olive oil, most meats, fresh veggies (like lettuce) in winter (but NOT summer), etc: basically, everything a 'cook everything from scratch, all the time' family uses.
- Cell phones: we're Canadian, so MMM's cell recommendations don't work for us. I needed to replace my phone this week. Going through the Costco kiosk to get the phone I wanted, with the carrier I wanted, with the plan I wanted - basically the same thing I would've done at the mall otherwise - just saved me 175$ (Ok, I got 175$ in costco coupons, but that's more than a third of my month's groceries paid for as a bonus of getting the thing I was going to get anyway)
- Gas IF we're going through there anyway.
- Electronics when they're something we're looking for anyway - they usually have better prices than the electronics chain stores, but it's easy to get suckered into buying something you don't need, so this is a 'proceed with A LOT OF CAUTION' zone.
Caveats:
- DO NOT get suckered into extra convenience food. Every bottle of dip, frozen pizza, etc is more expensive than making it yourself (with ingredients they sell!!!)
- DO NOT get suckered into buying ANYTHING not on the grocery list - impulse buy starts at 10$ per, which adds up REALLY FAST.
- Clothes can be worth it, surprisingly, IF you try them on, make sure they fit and you'll wear them, and return them right away if not. A pile of unworn clothes never helped anyone, and I've seen a few people fall into that mistake. That said, their socks last a long time, their leggings are comfortable, my sheepskin-lined slippers from there were affordable and are so warm and I love them, and their kid clothes are affordable, cute, and durable.
- BEWARE all the consumer goods. ONLY buy things that you need, are on your list, and that are at a price that's better than other stores AND you'll use the entire package (USB memory sticks are not a bargain if you have to buy more than you need, even if the price per unit is lower, for example).
- Kid's toys ONLY if it's something you'd been looking at anyway (last time I went, I found the EXACT THING I had been intending to buy my daughter for Christmas, but 30$ less than Amazon. Done. But not the 6 other 'oh this looks cute she'd love it' thing in the same aisle, those are a bad deal if you weren't intending to get them anyway!)
- Extra trips there aren't great. In my case, Costco is directly on my way home and less of a detour than the grocery store, so the convenience factor of getting all my staples and then cooking everything from scratch is pretty high... but a half-hour detour would kill that one.