From house brands to high end, Costco has something for everybody. And that has been the biggest secret to their success, and the key to their future.
Costco places all the fresh food in the back of the store (because that way shoppers have to go through the whole store first in order to get to the most popular items).
The brand names at Costco constantly change because Costco buys from whichever namebrand company overproduced that month.
Everything at Costco is constantly being reviewed for efficiency. The company recently changed the shape of their milk cartons to get rid of the empty space at the top. They can fill skinnier jugs all the way to the top, so they can get more gallons onto the same amount of space on a freight truck.
Costco's signature line is called Kirkland, and they have house brands of everything from wine to socks, candy and milk.