We love the "Co" but there are a few things to look out for. I had posted some problems with their pharmacy about a year ago which has gotten worse. They have some odd and strict rules that no other pharmacies have. I have asked many many other pharmacies about these rules and none are like Cpstco. Thing is that some (not all) of the pricing can be a huge discount compared to others. If you have a drug that you must have I would advise tht you have your doctor cut an additional script and use another pharmacy as a backup in case Costco screws you. Remember that you're shopping at a discount warehouse and that their pharmacists/employees act appropriately where you'll get discounted service and personality.
Costco's prices have been going up considerably in the last year. Some make no sense and they will give a bullshit answer that the mfg/producer is the one jacking the prices and that they only mark it up 15% or some such amount. They have been branding more products with their Kirkland brand name and these typically suck so be prepared. Be prepared to be up-sold to the "Executive" plan which is this business model big income producer.
Tires! Used to be a good deal but you can get screwed over here too. They keep a lowinverntory so you may be on a "back ordered" list to get a new tire if one is damaged. This happened to me twice. Their trick is to "up-sell" (again) you too a "better" tire which of course they will not just install one tire is must be to, store policy. Conveniently the two new tires most likely will not be the exact same size a the other two to which they will not rotate the tires since they don't match. Again their prices have gotten higher and Discount Tire is a better deal in price, availability and guarantees by far.
We like the products they sell so much so that we shop there for most everything to the tune of $8000 this year and counting. This does not include gas for my vehicle 30 gallons of premium at a time.
The vitamin, beauty, supplement dept isn't all bulk, either. One liquid joint supplement I used to take was literally 1/4 the price compared to CVS. Their Visine multi-pak was about half the cost of HEB, CVS, Walgreens. My first attraction years ago was the NSF 'metro' shelving units that weren't then available at the retail big boxes. Pretty much only restaurant supply houses carried them at a significantly higher price. At a >$25 savings on each unit, the membership paid for itself quickly.
Regarding fuel, I've found the Austin stores 87 octane price to be in line with other branded stations, but "premium" octane did run consistently 10 cents cheaper per gallon. However, Costco fuel is not guaranteed to be 'top tier' petrol, unless things have changed recently. I wouldn't hesitate to use it...just wouldn't use it exclusively.
I don't know their dog food prices; but their kibble is pretty highly rated...could add up if you have big or multiple pups. Folks who want to take the 'easy' route in vehicle shopping might benefit from the Costco vehicle buying service. I've heard of some pretty decent deals through Costco that the sales managers said would never happen without the Costco plan.
Now that they've opened the new Cedar Park store, I reckon I'll have to make a visit. It surely does pay to be able to shop during 'off hours'...although I've NEVER been in the Great Hills/Austin store when it wasn't crowded