The cheapest gas prices I have seen are $1.56 at two gas stations inside of 410 on Culebra Road.  The highest was $1.74 at Wurzbach and Lockhill Selma.  Highway 151 and 410 area is somewhere in the middle with $1.63, but Wal-Mart gas was the exception totaling $1.59/gallon.  The Thousand Oaks area is right around these prices.  Remember, these pennies do pile up.  A 20 cent difference over 15 gallons tacks on an additional $3.00 to your pocket book.  However, you also want to keep in mind the quality of gas you are filling your tank with.  Prominent stations such as Shell, Chevron, Valero, and Exxon most likely give you a higher chance at quality fuel.