Just went and saw the new Costco in Brisbane. Heaps of people lining up, heaps shopping. Had a look inside, was underwhelmed, and left.
The stuff there is slightly cheaper - you can get Huggies nappies for 0.40 rather than 0.46 for example. But not enough to justify the hassle of going there IMO.
I remember talking to taxi drivers and they would bang on about wow electronics or some other outlet that had "really good deals" and I think yeah whatever. I think Costco is the same thing - basically marginal bargains for bogans. The people who think they're being really sharp by ordering their phone off kogan and saving $20, or that think that anything cheaper than woolies or Coles asking price automatically qualifies as a "bargain".
A bit harsh to Costco considering Kogan's rep for service, but I think it is a reasonable analogy.
Costco works for people who want to be sure they aren't getting ripped off, but can't be bothered shopping around (a very American sentiment, I reckon).
They can be sure Costco has pretty good prices, all in one place.
Professionals will be able to get a better deal almost every time.
Although the $40 a case little creatures a couple of weeks ago was a pretty spectacular special!