Another "why's it so more expensive here" story.
The station near my house, a Citgo, is about $2.65 a gallon right now. Around the corner, on a very busy road, are a number of stations. The Sunoco is about the same price as the Citgo, the Shell a bit higher.
Near Castlekey's house about 10 miles away prices are running about $2.51 a gallon (there are 4 stations in very close proximity - Liberty, Sunoco, BP, and Shell. The Liberty is usually the cheapest by a few pennies, and the Shell the most expensive by a few pennies. A half mile away on the same road is an Exxon, which is normally about 15 cents a gallon more expensive. It's the only station that's visible in that area, so that probably drives the price somewhat.
Near where I shop, on a very busy road, is an Exxon. Again, it's the only visible station for about a mile or more in either direction, but certainly not isolated at all. Last night it was still sitting at $2.99 a gallon, and I suspect that it's going to be at that price for a long time.
It seems that in this area if a gas station isn't in eyeshot of another station, the price immediately jumps by 10 to 15 cents a gallon.