Greed or need: Why gas is cheaper in some parts of metro Phoenix?

Gas prices are starting to come down across the Valley (thank goodness), but some stations are markedly less expensive than others.

What's happening: Last week, I saw the QuikTrip at University Drive and Extension Road in Mesa charging just $3.90 per gallon.

• I drove 2.5 miles north and saw another QT charging $4.50. The Mobil across the street on McKellips Road and Country Club Drive was charging $5.25. What gives?

State of play: According to the National Association of Convenience Stores, gas stations, even those within a few miles of each other, often have different wholesale costs.

• Larger stations may be able to buy in bulk, bringing down their cost per gallon.
• Some stations are on more expensive corners than others, so they make up their real estate costs with higher gas prices.
• Stations may also carry different brands. Fuel that carries the name of a major refinery tends to cost more.

Yes, but: Sometimes, pricing is purely a business strategy.

• For instance, if a station is near the airport, right off a highway or in an otherwise convenient area, the prices will likely be higher because the owners know you're going to pay it.

Tips and tricks: GasBuddy is a popular website that shows the lowest gas prices in each ZIP code.

• After listening to radio ads about Upside for years, I finally downloaded it, and now I love it because it shows me gas prices near me and offers cash back at many stations.