I've been buying most of my gas at the local Costco for the last year or so. Prior to that there was an indie station with competitive prices. I shopped them because they were closer and I never had to wait in a line.

The dynamics of the local market changed about a year ago. Now, the Costco is $.40/gallon cheaper than the indie. The indie is still cheaper than the name-brand stations by about the same amount, so it's not that the indie stopped competing with them. I suspect Costco is selling its gas at an extremely small margin. Also, with how there's virtually always a line, despite 24(!) pumps, they're doing great volume.