See, I knew I wasn't the only one who loves that place. Their prices aren't as i-cant-believe-its-so-cheap (like Fry's) but they usually only stock high quality items, so you also know you're getting something good.
Costco "accounted for 11 percent of the organic milk and 40 percent of the Tuscan olive oil sold in the states during the same time period. It also sold $805 million worth of wine, a figure that included $390 million of fine wines. "
[from: Costco: Where tech changes, but hot dog prices don't CNET News.com ]