Peter,
I didn't say buy a Kirkland brand battery, I said buy an optima. You obviously are not familiar with them. They are the only new technology in batteries for many years. COSTCO just has lower markup by corporate policy than anybody else. Corporate policy is not to markup anything more than 14%.
Personally, I've had interstates and never had them last any longer than my autozone stuff. You will not get 14 years to your interstate- I probably will to my Optima. They're warrenttee program is full replacement for the first 3 years(no proration).
Interstates get hype because they let the service industry stock them for free. They only pay interstate when they sell one. So, that's why they are hyped more.
Of course you can buy it from Autoparts stores(I think Advanced sells them( or else where).
You swearing by interstates ,to me is exactly like swearing by Quakerstate dino oil for your diesel while I purchase the synthetic on the next shelf. Optima's are the new technology.
As far as products in general- I don't shop at walmart much. I buy quality items-ussually on sale. Clothing- I would never buy a $65 Pendleton shirt. That's me though- I would buy a nice REI shirt for $35 though.. of maybe a Pendleton for $30 at Norstrom's Rack. I own my Mercedes because it's safe and the seat is comfortable for my back. I know I could maintain something else cheaper, that might even last longer, but MB fits me well. They have the added advantage of the ability to find parts for older cars. No other make can you purchase a dash for a 30 year old car.
http://www.optimabatteries.com/products/index.asp
Sincerely,
Michael