I've been to Costco (UK) a couple of times. It mostly seems to be: 4x the quantity for 4x the price (i.e. same price as any other store). I don't get it? I honestly think a large majority of people think it being in bulk MUST equal a saving?

Is it just for like catering companies or families of 20 where the bigger size is kind of helpful?

They do some nice discounts on Macs online though (can't say I'm a fan of their customer service either though based on my experience returning a Macbook)